820-00840 20V 0A in S0 state

[jadao]

This one is a liquid damage board.
PPBUS_G3H is 13,06V, I got 20V and it charges the battery just fine.

Without battery it is stuck with 20V@0A

I am in S0 state and all rails on the power rail page are present except for the cpu:
PPVCCPU_S0G = 0V
PPVCCSA_S0G = 0V
PPVCCGT_S0G = 0V

On U7800
PM_PCHPWROK is missing
PMIC_SHUTDOWN_L is present 3V
Inputs VSA to VSH are all present
Input ENA to ENG are all present
input ENH is missing, R7874 is 0 ohm and PM_PGOOD_CPUVCC is 0V , there is no short and diode mode is 0,479.

On U7100, I confirmed that PM_PGOOD_CPUVCC is 0V
I made sure PP5V_S4 and PPBUS_G3H are present to VIN and VCC
PM_ENCPUVCC (ALL_SYS_PWRGD) is present, 3,3V on both sides of R7148.

Is it reasonnable to blame U7100 who must output PM_PGOOD_CPUVCC, I notice a via pad going to VIN (pin 41) was corroded so probably the chip took a hit, although it is well bonded with sillicone.

Thanks

 

[jadao]

I agree that much more signals are involved and required and anything can mess up the proper function of U7100.
I forget to mention that I started with a known working and ME cleaned bios but nothing changed.
I think this one may be a nightmare as it will be difficult to pinpoint a resistor, trace or simply a dead cpu

 

[jadao]

I replaced U7100 and it works now!!
I know it's an exceptional luck, specially that this chip is surrounded with sillicon there was no corrosion under it, but the ppbus_g3h burned via going into the chip leads me to believe it may took a hit... I replaced it out of desperation.
Will check now if it doesn't crashes after couple of minutes