[ Step 1: +VIN (19V/20V) Stabilizes via DC-In Chargers ] │ ▼ [ Step 2: +3VALW & +5VALW Regulars Activate Automatically ] │ ▼ [ Step 3: EC Chip powers up, reads BIOS firmware, waits for Power Button ] │ ▼ [ Step 4: User presses Power Button -> EC releases PM_PWRBTN# signal ] │ ▼ [ Step 5: CPU/PCH releases S3/S4 Sleep State indicators ] │ ▼ [ Step 6: ALL Switched Rails (+3V_VS, +5V_VS, +1.2V_VRAM) turn ON ] │ ▼ [ Step 7: CPU Core VRM fires up -> CPU receives ALL_SYS_PWRGD signal ] Stage 1: The Primary DC-In Isolation Circuit

Laptops do not power on all at once; they follow a strict, millisecond-fast sequence. If the sequence breaks at step 4, steps 5 through 10 will never turn on. Locate the in the LQV77 schematic. Check for +3VALW and +5VALW . Check the EC chip for the EC_RST# (Reset) signal.

Details the DDR slots, termination voltages, and data bus routing.

When the laptop is plugged into AC power but turned off, the rails are active.

Assume your LQV77 motherboard (Lenovo T480) is completely dead. No LEDs, no fan spin.