Lenovo Thinkpad L480 : 3VALW rail shorted to ground, but I can't find the shorted component

[mkdj]

Dear all,

Laptop is Lenovo Thinkpad L480 (boardview can be found in this badcaps topic). When pressing the power button the LED power light turns on, but nothing else happens.

I removed the motherboard, checked for shorts on the main inductors. I found that there is a short to ground on the +3VALW_P rail (@PL201). I soldered a wire on the PL201 inductor, and I injected up to 1.3V with my power supply. Current drawn is approximately 3.2A.

I used a small thermal camera to locate the shorted component. But nothing on the board heats significantly, except the CPU.

This is my first short circuit detection on a motherboard. Any advice on what I should do now?

Regards,
mkdj

[mkdj]

Dear all,

Because only the CPU is heating when injecting voltage on the 3.3V power rail, I conclude that the CPU is dead, and that the board is not fixable.

Thank you mon2 for your help.

Regards,
mkdj

[mon2]

nothing on the board heats significantly, except the CPU.

Most likely the defect is with the PCH (CPU) that uses the same rail.

[mkdj]

Thank you mon2 for your comment.

Does that mean that the CPU is dead, and the board can't be fixed without replacing the CPU?

What if I reflow or (try to) reball the CPU, could that solve the issue?

Regards,
mkdj

[mkdj]

Dear all,

Because only the CPU is heating when injecting voltage on the 3.3V power rail, I conclude that the CPU is dead, and that the board is not fixable.

Thank you mon2 for your help.

Regards,
mkdj