MACBOOK A1989 820-00850

[PITERPENY]

Hello. Need a fresh look. MacBook shows no signs of life.
When connected to USB-C with the battery connected, the consumption is 20V/0.220A and PPBUSG3H=11V.
If you disconnect the battery, the consumption will be 5V/0.220A and PPBUSG3H=12.3V
PP3V3_G3H=3.3V
PP5V_G3S=0V
PP1V8_SLPS2R =1.8v =0v=1.8v =... cyclically
voltage around u7800 appears/disappears cyclically.

[ugamazing]

Is PP1v8_SLPS2R shorted? It should be stable. Might be a faulty T2. Are other T2 rails stable or do they all cycle?

Also, the change in PPBUS when disconnecting battery is unusual; ppbus will be lower on battery and higher on charger(+batt). Have you tried testing board with a known-good case/battery and also DFU restore?

What work has been done on the board if any? Any signs of damage/liquid near any USB-C controllers at all? 20v/0a can be a ROM issue also, keep in mind. You can swap the ROM or reprogram with clean dump to be sure.