820-00850 20V not booting

No-Clean

Member
Clean board, no history.

Testing without battery and only charger connected:

20V and 0.030-0.170A on charger
12.6V on PPBUS for about 20 seconds then drops to 12.3V for about 2 seconds then repeats.
AWAKE and SLPS2R signals present but they restart as well around 20 seconds.
SSD voltages present

Restoring T2 gives error: Gave up waiting for device to transition from RestoreOS state to BootedOS state
 

2informaticos

Administrator
Staff member
Try DFU with both charger and (known good) battery connected.
Also try it disconnecting internal LCD; use external monitor for test.
 

No-Clean

Member
Restoring the T2 instead of reviving it did the trick, I also had better luck restoring with 10.15.7 than any other OS.
 

2informaticos

Administrator
Staff member
Thanks for feedback solution.
We need to collect as much as possible information about T2 machines.
Geting stuck in DFU make us thinking on other problems than firmware corruption.
Apple did "great job" on new machines...
 
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