820-00281 booting issues

[Kyle93]

Arrived with minor liquid damage in the U4200 area. Also some in the UB400 area.

Replaced a few capacitors affected by the liquid but no changes.

When board is booted you can hear the chime, see the apple logo on internal LCD but no progress bar ever appears. Using known good battery and apple original a/c adapter.

What should be checked next??

 

[2informaticos]

Disconnect J9600 and test with external USB macOS.

 

[Kyle93]

When booting from external USB macOS with J9600 disconnected the critical update screen appears and fails. Does this point more toward a SSD issue now?

 

[2informaticos]

Critical error appears because touchbar has its partition on internal SSD.
See if is possible to put machine in Target Disk mode, then check its SSD from other machine.

 

[Kyle93]

No reaction when trying to enter target disk mode, just the apple logo. Also have the Apple data recovery tool via J9600, tried that and drive never appears on the other macbook

 

[2informaticos]

Then internal SSD is bad.