M1 MacBook Pro A2338 2020 820-02020 stuck in a boot loop

[sekidata]

This 820-02020 had some minor liquid damage in the areas of UR630 (speaker amp), UD540 and UD560 (PP3V3).

It is stuck in a boot loop: it chimes, then begins to show the progress bar to around 15-20%, then shuts down and chimes again. This happens with every connector unplugged from the logic board, on battery or USB-C power. FMI is OFF. Holding the power button during startup proceeds to “Loading startup options”, then shuts down.

DFU Restore proceeds to Apple logo on the target machine with progress bar, but gets stuck at about 75% of progress bar, then restarts into the usual boot loop. The Restore fails on the host machine with error 9 (The System cannot be restored on this device).

 

[2informaticos]

Very likely leakage from PPBUS_AON to M1 data lines under UR630.

 

[sekidata]

There may be PPBUS leakage somewhere but I doubt it's near UR630. I cleaned that area and replaced UR630.

By the way, during every boot loop restart PPBUS goes to zero and USB-C voltage drops to 5V briefly.

 

[2informaticos]

The leakage happened BEFORE you've changed UR630.
Balls for data lines underneath are very close to PPBUS_AON.

 

[sekidata]

Which UR630 pins are you referring to?

 

[2informaticos]

The ones connected to M1.
Corrosion under UR630 caused overvoltage from PPBUS_AON to M1.
This is the first thing I suspect.

 

[thiben]

Hi Sekidata ! Ive the same problem ! Did you solve it ?