820-01987 not power up

[macRepairAmb]

Have this board that won't power up at first. Found missing PP5V_G3S. Isolated to U8110. PP5V_G3S restored once U8110 is replaced. But board still isn't powering up. The fan does spin but that's it. Any suggestions? Here are a few voltage readings

PPVCCGT_CPU_PH1/2 - 0.0v
PPVCC_CPU_PH1/2 - 0.85
ALL_SYS_PWRGD_R - 1.8
CPUCORE_PWM1/2 - 0.44
CPUGT_PWM1/2 - 2.5
SMC_PROCHOT_L - 0.0
CPUGT_FCCM - 0.0
L7410 Resistance is a little over 3.4ohms

Noticed the below. Not sure if it means anything
FB_A_CPUG - 0.0
while
FB_B_CPUCORE - 0.8

 

[2informaticos]

Did you try DFU mode?

 

[macRepairAmb]

Did you try DFU mode?

Yes. Both revive and then restore. It goes half way and just hangs for a long while before then switching to the locked symbol.

 

[2informaticos]

CPU coils get voltage?
Did you test USB activity?
Any reaction at Caps Lock LED?

 

[macRepairAmb]

PPVCCIO_S0_CPU - 0.96
PPVCC_CPU_PH1/2 - 0.85
PPVCCSA_S0_CPU - 1.02
PPVCCIO_S0_CPU - 0.95
PPVCCEDRAM_S0_CPU - 0.02

 

[2informaticos]

What about the other questions?

 

[macRepairAmb]

No usb activity. It lights up but doesn’t pulse
Cap light also doesn’t come on.

 

[2informaticos]

Did you test with internal LCD disconnected?

 

[macRepairAmb]

Yep and no image external.

 

[2informaticos]

I suspect CPU in this case...

 

[macRepairAmb]

So just as a last attempt at the board, not sure this was the actual fix, but i noticed U7710 had a short, so swapped it out. Was able to then do the DFU. The board appears to power up as caps lock comes on and off, there's usb activity and the laptop chimes when i plug in the power. I still don't have image on display or external. Still missing the below

PPVCCEDRAM_S0_CPU
PPVCCGT_CPU_PH1 and 2

 

[2informaticos]

EDRAM and iGPU voltages are not expected yet.

However, check diode mode to ground at L7702.
R7744/47 are both good?