PS4 SAB-001 no power after cleanup

[Jacksoft]

Hi everyone,
today we cleaned up from dust a PS4 Fat with SAB-001 motherboard and replaced the thermal paste with Arctic MX-4 (non conductive). Before disassembly the PS4 powered on normally but the fan was just loud because the dust.
We made many PS4 before, without problem and by being delicate in handling them.

Now, that's the strange part.

This PS4, after reassembly, just do a "beep" and immediately shutdown. After testing with another PSU we inspected the motherboard and found a blown fuse (F5104). Picture attached with some characters as traces notes.

There was no apparently short, just a low impedance, and the mosfet were good, so we replaced the fuse and retried again. Same thing after 1-2 seconds after power up.
Injecting 12V on the B trace (since in the A trace were 12V) does nothing, so no short. Also injecting 1V on the E trace (since it goes under the CPU) does not reveal any heat or short, checked with a thermal camera too.

Without mosfets, like in picture, in ohm mode, E trace measures about 50ohm and in diode mode measures 0.024.
I've found a PDF with some values written and ours are pretty low confronting with them.

Have anyone had this problem before?
Anyone know the voltage on E trace, when the console is on, just to try to inject the right voltage to check better?

I repeat, we just cleaned it up, and did nothing more.

Thank you.

[Jacksoft]

Re: PS4 SAB-001 no power after cleanup

Hi guys,
We finally figured out what happened and I'm writing how for who could have my same problem.
A friend of mine gave us a BLOD motherboard for voltage and other stuff references.
This line goes at about 0.90V 0.80Ah (there is another line that goes at about 1.10V 1.30Ah) in powerup/boot.
Our APU works correctly at this values and that was the strange thing, so we started to traceback all around the two mosfet on this line.

In final we found that during the disassembly (or moving the motherboard around) a band-pass capacitor connected on feedback(?) pin of the IC responsable of Mosfet working and operation was totally missing (pic attached).
This caused the IC to prompt the Mosfet to full current pass (this Mosfet goes at a maximum of 30V 45A) causing the short circuit between 12V and GND that blows up the fuse.
After putting a capacitor grabbed from the donor motherboard it started working perfectly!

It's so tiny that in first inspection we haven't noticed it!