MacBook Won't Boot After a Power Cut During a macOS Update? 9 Fixes (2026)

Laptop · macOS · Updated August 2026

The power goes out halfway through a macOS update, and when the electricity returns the Mac will not come back with it. You get a black screen, or the Apple logo sits there with a progress bar that never moves, or a folder with a question mark appears, or a spinning globe.

This looks like the worst thing that can happen to a laptop. In practice it is a software problem almost every time, the files are usually still on the drive, and there is a clear order to work through. The important thing is to stop pressing the power button repeatedly and follow the steps below instead.

⚡ The Short Answer

Plug the Mac into power and leave it alone for at least an hour first, because an interrupted update often finishes on its own. If it is still stuck, force restart it, boot into macOS Recovery, run First Aid in Disk Utility, and then reinstall macOS from Recovery. Reinstalling from Recovery does not erase your files.

First: Which Mac Do You Have?

Every recovery step below is different on the two kinds of Mac, and this is where most guides go wrong. Apple changed how recovery works when it moved away from Intel, so the old keyboard shortcuts simply do nothing on a newer machine.

APPLE SILICON M1, M2, M3, M4 — roughly 2020 onwards

You reach Recovery by holding the power button until the words Loading startup options appear. Startup key combinations such as Command + R do nothing on these Macs.

INTEL MAC Roughly 2019 and earlier

You reach Recovery by holding Command + R while the Mac starts. NVRAM resets and the other classic key combinations apply to these machines only.

⚠ Not sure which one you have? If the Mac will start far enough to show a desktop, open the Apple menu and choose About This Mac. If it will not start at all, go by age: a MacBook bought new from late 2020 onwards is almost certainly Apple Silicon.

Table of Contents

1. First: which Mac do you have?
2. Plug in and wait — do this before anything else
3. Force restart the Mac properly
4. Boot into macOS Recovery
5. Run First Aid in Disk Utility
6. Reinstall macOS from Recovery
7. Start in Safe Mode
8. Reset the NVRAM (Intel Macs only)
9. Rescue your files before doing anything drastic
10. Erase and restore from a Time Machine backup
11. Quick reference — all 9 fixes
12. Mistakes that make it worse
13. How to stop it happening again
14. Frequently asked questions

The 9 Fixes, In Order

1Plug in and wait — do this before anything else

HIGH IMPACT DO THIS FIRST 60 min NO DATA LOSS

When power returns, a Mac that was mid-update frequently picks up where it left off. The screen can look completely frozen while it does this, because the progress bar only moves when a file finishes writing and some of those files are very large. People give up after ten minutes and force a shutdown, which turns a recoverable situation into a broken one.

Steps

1. Connect the Mac to its charger and to a working outlet. Do not attempt any of this on battery.
2. Leave it completely alone for at least one hour. Two is better if the Apple logo and a progress bar are visible.
3. Watch for any sign of life: a bar that inches forward, the fan changing speed, or the screen brightness shifting. Any of these means it is still working and you should keep waiting.
4. Only when there has been no change at all for an hour should you move to Fix 2.

✅ Verify it worked: the Mac finishes the update on its own and reaches the login screen.

2Force restart the Mac properly

MEDIUM IMPACT 5 min NO DATA LOSS

A single clean force restart clears a hung boot process and costs nothing. What causes damage is doing it over and over, because each forced shutdown risks interrupting another write to the drive.

Steps

1. Hold the power button down for about fifteen seconds, until the screen goes black and every light and fan stops.
2. Wait a full thirty seconds with the Mac off. This lets the hardware fully discharge.
3. Press the power button once and let go.
4. If it is still stuck after this, do not repeat it. Move to Fix 3.

⚠ One force restart, not five. Repeatedly cutting power to a Mac that is writing to its drive is the single most common way people turn a fixable update into a wiped one.

✅ Verify it worked: the Mac boots to the login screen or resumes the update.

3Boot into macOS Recovery

HIGH IMPACT 10 min NO DATA LOSS

Recovery is a small separate system stored on the drive, and it works even when the main installation is broken. Everything useful from here on happens inside it. This is also the step where the two kinds of Mac diverge completely, so use the right one.

On an Apple Silicon Mac

1. Shut the Mac down fully, then wait ten seconds.
2. Press and keep holding the power button. Do not let go when the Apple logo appears.
3. Keep holding until you see Loading startup options, then release.
4. Click Options, then Continue.

On an Intel Mac

1. Shut the Mac down fully, then wait ten seconds.
2. Press the power button and immediately hold Command + R.
3. Keep holding until the Apple logo or a spinning globe appears, then release.
4. If a globe appears, the Mac is loading Recovery over the internet. That is normal and needs a Wi-Fi connection.

✅ Verify it worked: you reach the macOS Utilities window listing Restore, Reinstall, Safari and Disk Utility.

4Run First Aid in Disk Utility

HIGH IMPACT 20 min NO DATA LOSS

Cutting power mid-write leaves the drive’s index of where files live out of step with the files themselves. First Aid rebuilds that index. This is the fix that rescues a large share of Macs that will not boot after a power failure, and it does not touch your data.

Steps

1. In the Recovery window, choose Disk Utility and click Continue.
2. In the menu bar, click View → Show All Devices. This matters, because you need to repair in the right order.
3. Start at the bottom of the sidebar list and work upward: repair the volumes first, then the containers, then the physical disk at the top.
4. Select each item, click First Aid, then Run, and let it finish before moving to the next.
5. When the whole list is done, quit Disk Utility and choose Restart from the Apple menu.

Note: if First Aid reports that it could not repair the disk, do not run it again in a loop. Go to Fix 8 and get your files off the machine first.

✅ Verify it worked: every item reports that the operation was successful, and the Mac boots normally afterwards.

5Reinstall macOS from Recovery

HIGH IMPACT 60 min NO DATA LOSS

This is the step that actually finishes the job the power cut interrupted. Reinstalling from Recovery replaces the system files and leaves the part of the drive holding your documents, photos and applications untouched. It is not the same as erasing the Mac, and it is worth being clear about that because the wording frightens people into skipping it.

Steps

1. Back in the Recovery window, choose Reinstall macOS and click Continue.
2. Accept the terms and select your startup disk, normally called Macintosh HD.
3. Make sure the charger is connected and stays connected. If your power supply is unreliable, wait until it is not, because a second interruption here is worse than the first.
4. Let it run. It downloads the installer and can take an hour or more, and the Mac will restart by itself several times.
5. Do not close the lid and do not touch anything until you reach the setup or login screen.

⚠ Recovery installs a current version of macOS, not necessarily the exact one you were updating to. That is fine. Once the Mac boots, you can install any remaining updates normally.

✅ Verify it worked: the Mac reaches the login screen and your files and apps are where you left them.

6Start in Safe Mode

MEDIUM IMPACT 15 min NO DATA LOSS

Safe Mode loads only what macOS needs and runs a check on the startup disk while it does. If the Mac boots here but not normally, something you installed is the obstacle rather than the update itself. As with Recovery, the method differs by processor.

On an Apple Silicon Mac

1. Shut down, then hold the power button until Loading startup options appears.
2. Select your startup disk, then hold Shift and click Continue in Safe Mode.

On an Intel Mac

1. Shut down, then press the power button and immediately hold Shift.
2. Release Shift when the login window appears. You should see Safe Boot in the corner.

Once you are in, restart normally. Simply passing through Safe Mode repairs some startup problems on its own.

✅ Verify it worked: the Mac reaches the desktop in Safe Mode, and then boots normally after a restart.

7Reset the NVRAM (Intel Macs only)

MEDIUM IMPACT INTEL ONLY 5 min NO DATA LOSS

NVRAM is a small piece of memory that remembers which disk to start from. A power cut can leave it holding a startup disk that no longer exists, which produces a black screen or a question-mark folder even though the drive is perfectly healthy.

⚠ Skip this entirely on an Apple Silicon Mac. There is no key combination for it and no separate SMC to reset either. Those Macs check and reset the equivalent settings automatically every time they start, so any guide telling you to reset the SMC on an M-series machine is out of date.

Steps

1. Shut the Mac down completely.
2. Press the power button and immediately hold Option + Command + P + R together.
3. Keep holding for about twenty seconds, then release.
4. Let the Mac start normally. You may need to reset the time zone and volume afterwards, which is expected.

✅ Verify it worked: the Mac finds its startup disk and boots instead of showing a question mark.

8Rescue your files before doing anything drastic

HIGH IMPACT BEFORE ERASING 45 min

If the reinstall has failed and you are being pushed toward erasing the drive, get your data off first. Recovery includes a full Terminal, and the drive is usually still readable even when macOS will not boot from it. Do this before you agree to erase anything.

Steps

1. Boot into Recovery as described in Fix 3 and plug in an external drive with enough free space.
2. From the menu bar choose Utilities → Terminal.
3. Type cd /Volumes and press Return, then type ls and press Return to see the drive names.
4. Use the cp -R command to copy your user folder from the internal drive to the external one, for example copying the Documents, Desktop and Pictures folders in turn.
5. Check on another computer that the copied files actually open before you erase anything.
6. If Terminal is not something you are comfortable with, an Apple Store or a repair shop can pull the data off in one visit. That is a reasonable thing to pay for.

✅ Verify it worked: your files are on the external drive and open correctly on a different machine.

9Erase and restore from a Time Machine backup

MEDIUM IMPACT LAST RESORT 2 hours

When the drive cannot be repaired and macOS will not reinstall over the top of it, the remaining option is to wipe it and put everything back from a backup. Only do this after Fix 8, and only if you genuinely have a recent backup.

Steps

1. Boot into Recovery and connect the Time Machine drive.
2. Choose Restore from Time Machine Backup and pick the most recent backup taken before the power cut.
3. If the restore itself fails, open Disk Utility, erase the startup disk using the APFS format, then reinstall macOS and use Migration Assistant to bring your data back during setup.
4. Keep the Mac plugged in throughout. A restore takes considerably longer than an install.

✅ Verify it worked: the Mac boots into your account with your files and settings in place.

Quick Reference — All 9 Fixes

#	Fix	Applies to	Time
1	Plug in and wait	Both	60 min
2	Force restart once	Both	5 min
3	Boot into Recovery	Both, different method	10 min
4	First Aid in Disk Utility	Both	20 min
5	Reinstall macOS	Both	60 min
6	Safe Mode	Both, different method	15 min
7	Reset NVRAM	Intel only	5 min
8	Rescue files via Terminal	Both	45 min
9	Erase and restore backup	Both	2 hours

Mistakes That Make It Worse

• Force restarting again and again. Every forced shutdown is another chance to interrupt a write. One is a reasonable test; five is how a repairable disk becomes an unrepairable one.
• Erasing the drive before copying the files off. Once it is erased, the files are gone. Fix 8 exists for exactly this reason.
• Working on battery. If the battery runs out during a reinstall you are back where you started, only worse. Stay plugged in.
• Using Intel instructions on an Apple Silicon Mac. Holding Command + R on an M-series machine does nothing at all, and people conclude their Mac is dead when Recovery was always available.
• Closing the lid during the reinstall. It can suspend the process partway through.

How to Stop It Happening Again

• Start updates on a full battery and leave the charger plugged in. A MacBook with charge in the battery survives a power cut during an update. That is the whole trick.
• Turn Time Machine on. An external drive and one setting is the difference between an inconvenient afternoon and losing years of files.
• Do not update during a storm or at a time of day when your supply is unreliable. Updates can always wait.
• Run First Aid occasionally. Catching disk errors before an update is far easier than after one.

Frequently Asked Questions

Will I lose my files?

Usually not. Fixes 1 through 8 all leave your data alone, including reinstalling macOS from Recovery. Files are only at risk if you erase the drive, which is why Fix 8 comes before Fix 9.

The Apple logo has a progress bar that has not moved in 40 minutes. Is it frozen?

Not necessarily. The bar moves in jumps rather than smoothly, and a large system file can hold it in one place for a long stretch. Give it a full hour of no change before treating it as stuck.

Command + R does nothing on my MacBook. Is it broken?

Almost certainly not. If it is an Apple Silicon Mac, that shortcut does not exist any more. Hold the power button instead until Loading startup options appears, as described in Fix 3.

Should I reset the SMC?

Only if you have an Intel Mac, and even then it is rarely the answer for this particular problem. Apple Silicon Macs do not have a separate SMC to reset, so any instruction to do so does not apply.

Can a power cut damage the hardware?

It is uncommon. The overwhelming majority of these cases are software and disk-index problems. If the Mac shows no sign of life at all with a known-good charger connected, that is worth having looked at in person.

A folder with a question mark appears. What does that mean?

The Mac cannot find a system to start from. Sometimes the drive is fine and only the startup setting was lost, which Fix 7 handles on Intel machines. Otherwise go to Recovery and run First Aid.

How long does the reinstall take?

Around an hour on a decent connection, sometimes longer, because Recovery downloads the installer before it starts. Several automatic restarts along the way are normal.

I have no backup and nothing is working. What now?

Stop trying fixes and get the data off first, using Fix 8 or a repair shop. Every additional attempt on a failing drive is a small risk, and recovering the files matters more than recovering the installation.

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