820-01700 20V no power

[No-Clean]

Board had issues with U2890 and UB090 and was stuck in 20V, fixed that and now I get to 20V but no power and no detection in DFU.

SSD power is missing.

PMU seems to be working fine.

SLPS2R and Awake signals ok but PP1V2_AWAKE_SOC_PLLSOC_F is 0.7V not sure on that one, diode read OK.

 

[2informaticos]

Try external switch method to force DFU.
Disconnect Touch ID and add a second switch for PMU_ONOFF_L.

 

[No-Clean]

Tried but no luck, I even tried my force DFU method on a different board and that other board did enter DFU, but not this one.

Here is my method just in case:

1. Short the Force DFU test point (PMU_FORCE_DFU) to any 1.8V line
2. Connect restore cable to the correct port for T2 restore
3. Connect to power using a charger and a different USB port after step 2

 

[No-Clean]

SSD rails all get 0V

 

[2informaticos]

Then you may have problems with T2 chip...

 

[No-Clean]

Ok after checking some more I found PP1V2_S3 to be low in diode read 0.050 vs 0.225 when I inject 1.2V on that line the RAM chips are the only ones getting some temperature.

 

[No-Clean]

Should I kiss this one adios?

 

[2informaticos]

You can try changing RAM chips...