Macbook Pro 16 M1 2021 - Stuck in boot loop, power button hold not working

OK, iStore in Cape Town (recommended by Apple since there is no Apple Store here) echoed my results on their attempts to do the same - they are recommending replacement of Logic and Touch ID boards ($1000 USD with labor). I have an extended warranty with my credit card company and will likely have them attempt the repair.

Asked and they said trade-in is worth $0 in its current state.

Sent for repair. Issue was determined to be as you predicted, both Display + Lid Angle Sensor were replaced for $748.

Unfortunately, they also performed a clean install of MacOS for whatever stupid reason, so data was wiped.

Again majority of my stuff was in iCloud but still bummed about the things I did lose that were in local pictures/movies/music/downloads/home directories.

Also really stupid that a broken lid angle/display means that MacBook can't boot when lid is closed, display is off, and connected to an external monitor.

Connect the computer to the Apple Charger using the Apple suppled cables

This article from Apple regarding Apple Silicon Computer and accessing the Recovery Mode

refer below

Use macOS Recovery on a Mac with Apple silicon - Apple Support (CA)

Excerpt below

Start up your computer in macOS Recovery

1. On your Mac, choose Apple menu  > Shut Down.
2. Wait for your Mac to shut down completely. A Mac is completely shut down when the screen is black and any lights (including in the Touch Bar) are off.
3. Press and hold the power button on your Mac until the system volume and the Options button appear.
4. Click the Options button, then click Continue. 
5. If asked, select a volume to recover, then click Next.
6. Select an administrator account, then click Next.
7. Enter the password for the administrator account, then click Continue.
8. When the Recovery app appears in the menu bar, you can choose any of the available options in the window or the menu bar.

Restore attempts failed. I am 100% sure there is a hardware issue, I am guessing with the Touch ID board and/or the Logic Board sadly. I will have to wait to confirm, sending the MacBook to the iStore in Cape Town to check it.

SOLVED. It was indeed the Display and Lid Angle Sensor - either/or - it is repaired and coming home to me tomorrow.

Only bummer, they could have left the data alone had we known. I had a back-up but it would have saved me the time on a restore and then data merge from my loaner MacBook (my wife's, thanks dear).

Yes, I unplugged the display cable, cleaned the port with soft brush, I was able to identify the port using one of the ifixit tutorial

Agreed, this is a hardware issue, not OS related. If you do not attempt a restore or change out the MLB, you'll be able to keep your data.

I believe the problem is either the LCD Screen Angle Sensor and/or the Display. My cost to repair was around your quote.

If you want to save your data and to keep your M1 MBP, just pay the $748. If you later decide you don't want your MBP and want to upgrade, you can trade-in at close to $600 - costing you $148 to save your data.

My 2 cents.

Then have a few suggestions ;

1 - Have the computer evaluated by the Professionals who have the Special Hardware Software and Expertise to diagnose the issue and offer possible solutions

2 - Make an Appointment at the Apple Genius Bar and have them evaluate the computer

So back together. Still not fully booting.

It isn't looping anymore and the back-light is still down. I can see the apple logo appear very briefly when I press the power button while a flashlight is used to light the screen, but it disappears very quickly and never boots. Holding the power button down is different now too - the Apple stays on while I hold the power button, but I never get the boot options menu.

I'm pretty sure it is not passing the hardware test on boot-up hence this behavior. Looks like I have to bring it to apple when I return to the states.

So the latest update. MLB was replaced and did not change the symptoms. This is not a logic board issue (I did not think it would be), now they are replacing the Display Assembly (which I suspected in my initial post) and the LID Angle Sensor (which I did not even know existed) which makes sense because when I would lift the lid it would attempt to boot on its own. I have a suspicion that the power/ID board is also bad, which if true will be the next component they identify and faulty. Exciting stuff! ;) Stand by for more...

Found another discussion about this: 2021 Macbook M1 Boot Loop Issue Solved - Apple Community

Surprisingly I'm having the exact problem with my 14inc m1 pro 2021, screen just went blank, apple faded logo is showing on the screen if you use a flashlight or touch, the logo is just blinking and looping till it disappear again, no blacklight from the display, I'm really fustrated, it started this morning, hopefully a solution is pro ided for us without a need to visit service center because I can't have access to any service center here for now

I think you’re on to something - I tried the flashlight idea and I have the same pattern, it definitely feels hardware related to me, particularly since holding the power button down, does nothing, I can’t get to the boot menu. A firmware recover did not work. It crashes every time in the middle of the process.

I'll be taking it apart this week to take a look... I'll update after.

I'm hoping it just took a hit and a cable is lose/ torn - I used to be a Mac tech, and 50% of the time when you take one apart you can find the issue. The fact that we both lost our backlight is telling of a hardware issue.

Stand by...

Thanks for replying P. Phillips - as the title indicates, the usual recovery is not working - that is it does not interrupt the boot loop, I think it is not passing the hardware test to begin the disk-boot process. So the awful fix-all button Apple put on firmware is not helpful.

Restoring the firmware failed as-well. Tried it multiple times.

Also in the thread, I am overseas, Africa to be exact - no Genius Bar here. ;)