Spotless 820-02917 20V with missing PP1V8_UPC0_LDO

[overshoot]

Hello,

I am working on that board that doesn't have schematic/boardview.
The closest boardview available is the 820-02935.
The board under the microscope is spotless.

With a thermal camera, I can see the circuitry creating PPBUS_AON is warming up and I get an inrush current of 200mA for less than a second.
Then the area cools down and the current draw is near 0A.

A DFU restore fails with error 4047.
I've tried a couple of times.

Here is what I've measured so far:
I have PP3V8_AON stable at 3.78V
PPBUS_AON went from 12.3V to 12V
PP1V8_AON_LPMU is at 1.8V stable
PP1V2_NAND0 is at 1.2V and PP0V9_NAND0 is at 0.85V
I have 3.3V on PP3V3_UPC0_LDO
I have 3.3V on PP3V3_S2
I have 1.5V on PP1V5_UPC0_LDO_CORE

But I have 0V on PP1V8_UPC0_LDO (Rail missing)

PP1V8_S2 is present at 1.8V
PP1V8_UPC1_LDO is also missing.

UPC0_AUX_DET_SHORT is jumping to 3V then back 0V
I have .46V drop on both USBC0_CC1 and USBC0_CC2 lines
I have .74V drop on both USBC0_SBU1 and USBC0_SBU2 lines
I have .29V drop on both USBC0_AUX_N and USBC0_AUX_P lines

 

[2informaticos]

Disconnect RH030/1/3/4 one by one and find which port generates the issue.

 

[overshoot]

Thanks!
Removing RH030 connected to U5500 (magsafe port) is what caused the CHGR_AUX_DET_SHORT to stop jumping.
Does that mean the SN24A12 is toast and needs to be sourced from a donor or possibly something connected to it is causing the short?

 

[2informaticos]

So your problem should be located on the Magsafe area.
Compare diode mode readings around U5500 with another SN24A12 chip.