ROG GL702 - now turns on but no post

[magneh]

Hello!
Got this ROG laptop dead, with missing charging battery IC and some bad mosfets.
Replaced everything and laptop now turns on as soon as I plug in DC power, but no image.

Tried 2 BIOS dumps, EC IT8995VG-128/DX was replaced with a new one, but still no POST.

Measured some signals around EC

B7 PM_SYSPWROK 3.3V
D8 PM_CLKRUN# 3.05V
E8 P_SMB3_CLK 0V
F4 PCH_SUSACK# 3.3V
F9 IMVP8_PWRGD 3.05V
G12 ALL_SYSTEM_PWRGD 3.3V
M4 BUF_PLT_RST# 0.4-0.77 and changing

So when I found BUF_PLT_RST oscillating, I narrowed it down to U2401
PLT_RST is present as also +3Vsus, so just for testing, I shunted PLT_RST to BUF_PLT_RST

Signal came up to 3.3V and board now takes -+ 1,3Amps , but still no post.
Removed the short, and BUF_PLT_RST is 0V at the start, then goes to 2V after a few mins and fans start spinning full speed.
Then keeps oscillating value...
PCH is fairly warm, CPU/GPU coils are also fairly warm. GPU and CPU are not heating up much

Is there something I could also check regarding clock signals or something else?
Bad PCH?

Any help is welcome, running out of ideas... and maybe knowledge

Thanks!

[piernov]

Re: ROG GL702 - now turns on but no post

Maybe you have something on BUF_PLT_RST# pulling to low.
I'd first replace U2401 to make sure it's not the issue, then disconnect the jumpers and resistors on BUF_PLT_RST# one by one.

[magneh]

Re: ROG GL702 - now turns on but no post

Maybe you have something on BUF_PLT_RST# pulling to low.
I'd first replace U2401 to make sure it's not the issue, then disconnect the jumpers and resistors on BUF_PLT_RST# one by one.

Yes, I suppose its U2401, as value is oscillating, sometimes is 0, then goes to 2 volts +-, then 0.77 ... its randomly having weird values.

When its 0, I get less amps on the PSU. when it goes to around 2V I get more current consumption but still no post.

When shorting it to PLT_RST, it stays stable at 3.3V but still no boot

[magneh]

Re: ROG GL702 - now turns on but no post

RIP!

Thanks all!