Dell Latitude 14 rugged 5404 - half dead

[DrFalken]

Hello!
A client brought a Dell Latitude 14 rugged 5404 that looks like half dead.
In short, pressing power button:
- power led turn on for 17 seconds
- nothing more (black screen, fan not spinning, no sound)
I've already:
- cleared CMOS
- changed RAM
- backed up original BIOS & flashed A18 BIOS (1x 4MB + 1x 8MB chip) using istructions on https://www.badcaps.net/forum/showthread.php?p=1010808
What else can I check ?
I'm looking for board schematic & boardview.

[DrFalken]

Re: Dell Latitude 14 rugged 5404 - half dead

Some readings attached.
5V is always present.

[FrozenHaxor]

Re: Dell Latitude 14 rugged 5404 - half dead

What about the other rails? 3.3V, Vcore, Vram? Is heatsink getting hot?

When you programmed the chips did they pass read verification against master file?

[DrFalken]

Re: Dell Latitude 14 rugged 5404 - half dead

What about the other rails? 3.3V, Vcore, Vram? Is heatsink getting hot?

Will check that with schematics and report back.

When you programmed the chips did they pass read verification against master file?

Yes!

[DrFalken]

Re: Dell Latitude 14 rugged 5404 - half dead

Turned OFF / ON:
+3.3V_M (@BIOS) = 0 / 0
+VCC_CORE (@PC5612) = 0 / 0

VRAM to be measured...
Heatsink is cold

[DrFalken]

Re: Dell Latitude 14 rugged 5404 - half dead

+1.05V_RUN (@CC78) seems to be short to GND
Removed CC78, still shorted.
Removed LC6:
- CC78 not shorted anymore
- pin1@LC6 (+1.05V_RUN) still shorted to GND
Removed L77 & L78 but +1.05V_RUN is shill shorted to GND.

[reformatt]

Re: Dell Latitude 14 rugged 5404 - half dead

Usually shorted 1.05V rail is a dead PCH.

[DrFalken]

Re: Dell Latitude 14 rugged 5404 - half dead

Removed CC71, C389, CC55, CC79 but +1.05V_RUN is still shorted.
Injected 0.8V 1A on CC71 pin1 (+1.05V_RUN), found 0.08-0.10V on remaining caps belonging to 1.05V rail (CC33, CC34, CC37, CC60, CC63, CC64 just below the MCH)
As said by @reformatt I think the PCH is dead.