Lenovo Yoga 9I 15IMH5, MB LC40CM Won't Turn On, 1V_VCCGT is not present

[air_chair256]

Hello,

I have a Lenovo MB LC40CM 19863-1 when press button is pushed the keyboard backlight turns on and off twice and the power button light keeps blinking and the fans spins for a few seconds and stops then again spins and stops (Three times) then laptop turns off. no image on screen. sometime when you leave it for few days it will turn on and work but once you restart it won't turn on.

Tried to reball RAM 1,2,3,4
Checked all voltages on big coils all present except 1V_VCCGT is not present I get 0V on this rail. is this voltage should be present once power button is pushed? or does it get activated later in next stage?

I tried to ask for Bios on here and it was sent to me wrote it into the chip but still same issue.

any ideas on what can be the possible issue or where to check?

Thanks

[Sephir0th]

+VCC_GT is not a requitement for succesful P.O.S.T.

Soldered RAM could be indeed a issue here. A reball of course wouldn't help, if the device wasn't dropped by any chance or suffers from similar physical pressure. A dead chip is a dead chip.

However, a approach into this direction could be to measure resistance to GND of the RAM related power rails. Maybe the DRAM_RESET logic tells something too.