MacBook Pro doesn’t load after software update

If you're installing a macOS update or upgrade

When you're updating or upgrading macOS, the Apple logo or progress bar might persist for much longer than usual. As installation continues, the progress bar might move slowly and pause for long periods. Apple recommends starting installation in the evening—so that it can complete overnight, if needed.

If your Mac is stuck on this screen or keeps restarting

If startup never progresses beyond an Apple logo or progress bar:

1. Press and hold the power button on your Mac for up to 10 seconds, until your Mac turns off. (Every Mac has a power button. On laptop computers that have Touch ID, press and hold Touch ID.)
2. Turn your Mac back on. 
3. If the issue persists, press and hold the power button until your Mac turns off. Then unplug all nonessential accessories from your Mac, including printers, drives, and USB hubs. You could have an issue with one or more of those devices or their cables. 
4. Turn your Mac back on.
5. If the issue persists, once again press and hold the power button until your Mac turns off. 
6. Try to start up from macOS Recovery and repair your startup disk as described in this article: How to repair a Mac disk with Disk Utility.
7. If the issue persists, try to reinstall macOS from macOS Recovery.

If your Mac continues to start up to an Apple logo or progress bar, it might need service. Get service.

Try booting into Safe Mode. You may have some third party software installed which is interfering with the normal operation of macOS.

Start up your Mac in safe mode - Apple Support

AndreAC10 wrote:

Hi everyone, I started the software update for macOS Sequoia 15.6 yesterday evening and my Macbook Pro M1 is already loading.

After it restarted as usual in recovery mode, I turned it off and started it again and, after the login,

now the screen remains black with the apple logo and the loading bar (always stuck at the same point, near the start) on the bottom of the screen.

It has been stuck like this for 2 hours now, anyone knows how to resolve?

[Re-Titled by Moderator]

You can always force quit a shutdown by holding the power button/TouchID for ~6-10 sec.

Force Shut down your Mac. You can try reboot as normal and compare your results or SafeBoot mode as suggested above.

Log out, sleep, wake, restart or shut down your Mac

Shut down or restart your Mac - Apple Support

no resolve—

If your Mac starts up to an Apple logo or progress bar

ref: If your Mac starts up to an Apple logo or progress bar - Apple Support

AndreAC10 wrote:

After it restarted as usual in recovery mode, I turned it off and started it again and…

Booting to the Recovery OS during a macOS update is NOT usual. Seeing a black screen is normal, as is seeing just the Apple logo and a progress bar, but at the end of the update process you should see the normal login screen. If you see the recovery options and need to manually restart, there’s a problem.