M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

[mitchw]

I have a liquid damaged 820-02016 that has a 1-2mm wide hole in the PCB caused by a burned capacitor. The PPBUS_VON is shorted. I think the board is 100% gone, I tried grinding off the burned PCB material with no avail, the board is burned almost through to the other side.

But, I can get a fully working iCloud locked mainboard for very cheap.

As far as I have seen, there are only two ROM chips on the board, the TBT ROM and main flash.

Is it possible to transfer these two ROMs from the bad board to the good locked one and "unlock" the good one in that manner?

[ugamazing]

Re: M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

Nope. But, if you swap the M1 CPU and the WiFi card over to the locked board, yes, it will work. Be prepared for a brutal 4-6 hours of work though.

[mitchw]

Re: M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

Oh okay. Thanks. Apple really made it hard this way...

I managed to repair the board. It was a 4 hour job, I found the shorts inside the PCB and removed them, and repaired the traces for one of the chip that was above. Laptop now turns on and comes up to the login screen.

But there are still problems:
- Trackpad and keyboard aren't working. Found the corroded trackpad and its cable. Trackpad itself might be salvageable, but one resistor fell off during cleaning. There is probably no schematics for the trackpad...?
- Keyboard not working, I guess it is the same matter as on Intel MacBooks, where it needs to see the internal trackpad for the keyboard to work?
- I can't reset the laptop as the user login password is lost (but Find My is turned off), as it will ignore USB-C keyboard keystrokes. Any other way to do it?
- Battery will not charge. Everything looks nice, the battery isn't liquid damaged, the SMBUS lines look fine. Battery voltage (on the battery PCB) is 11V. Anything particular to look for?

[obelix24]

Re: M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

connecting external keyboard ?

[mitchw]

Re: M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

connecting external keyboard ?

Yes. It works on login screen, but will not go into recovery via CMD+R.

[obelix24]

Re: M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

it should work also to recovery maybe try another keyboard ? or try original apple wired keyboard

[mitchw]

Re: M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

I am using an original apple wired keyboard...

[reformatt]

Re: M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

CMD + R no longer works on the newer MAC's. You got to hold down the power button till the options menu comes up.

[mitchw]

Re: M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

Oh ok, didnt know about this, despite having a 16 inch M1 MacBook for a year now.

I managed to restore it now. The battery says “Service now”. So I guess battery is itself bad..?

[obelix24]

Re: M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

maybe it's just so discharged that is locked .... check video of Electronic repair school : Fixing/Unlocking laptop batteries without any software
shortly maybe if possible just charge it little bit with power supply and it will work again

[mitchw]

Re: M1 MacBook Air 820-02016 possible to swap ROMs to unlock a locked board?

I took the battery out and on the bottom side of the battery PCB there was some corrosion.
One resistor was particularly corroded, and it later fell of when I tried to measure it. It read OL even after off the board.

I guess there isn't much to save with this battery. Or if someone has the value of the resistor and I can resolder it back...