Dell G5 SE 5505 Random boot loop

[Andreasbest]

Hello.
I bought a G5 for my self, at a low price, i knew it was faulty, so the fault is that does random boot loops.
I tried RTC reset, BIOS update, replaced thermal paste with MX-5, checked fans for dirt, disconnected all flex cables (daughterboard usb, keyboard, trackpad, wifi, m.2, replaced RAM) but still the same.
This behavior can be a faulty GPU/CPU or if any of these components get faulty the laptop shut down completely?

When i get luck and enter Windows i see everything in device manager without exclamation marks.

Any advices or thoughts welcomed

[kalilinux25]

if you boot in bios those it reboot? try remove outboard test

[Andreasbest]

I think in BIOS and DIAG screen it doesn't reboot, i'll test it again.

What do you mean to remove outboard test?