Trace the B+ rail across the board. Check ceramic decoupling capacitors near the CPU and GPU phases, as these are prone to cracking and shorting directly to ground. 2. Missing +3VALW and +5VALW Rails
The EC releases the system suspend states ( PCH_RSMRST# and SLP_S3# / SLP_S5# signals). asl50 lac921p rev 10 schematic exclusive
If the board powers on but fails to POST (Power-On Self-Test), the schematic is used to track high-speed signals like (BIOS data to the EC), SMBus (communication between the PCH and power chips), and LPC (Low Pin Count) bus. Trace the B+ rail across the board