Lenovo Legion 5 Pro 16ACH6H Type 82JQ – Shorted EC Chip

Hello,

On pressing the power button, keyboard backlight illuminates and the fans spin for a couple of seconds, then go off. Light on power button stays on. The cycle then repeats.
I discovered that the EC chip has a crack in the top. It is taking 400mA at 0.8v. Also, the capacitors surrounding it read as shorted to ground.
I’ve removed the chip and the capacitors are no longer shorted to ground.

Before replacing the chip, I would like to try and find what caused the chip to die in the first place, as I’m worried that if I solder in a new chip, it will suffer the same fate as the original one.
With the chip removed, I’ve checked all of the pads for resistance to ground. The only pads which produce 0Ω are numbers 1, 27, 49, 75, 91 and 104, which is correct as they are all ground pins.
I’ve checked voltages at the buck converter (Richtek RT6585C) and have 20.5v on pin 12, 3.3v on pin 3 and 5v on pin 13, which all seems to be fine.

What other checks should I be carrying out before installing a new EC chip?

Motherboard number is HY660 HY661 HY561 HY572 HY56C HY57K NM-D562 Rev 2.0.

Thank you.

Check the DC socket if there are any signs of damage, crack etc. Most often the KBC dies when there is problem in the DC socket area. Also check the power supply socket.

There is also a slight possibility of PCH\CPU damage when DC+ gets shorted to ACID

You can try to supply 20.5V on the DC jack to check if the APU gets hot even without a working KBC. If it does, then damage to the PCH part of the APU is very probable.

Have checked the DC socket. Everything looks good, no signs of cracking, burning or damaged contacts. Have checked inside the port using a microscope.

Applying 20.5v at the DC socket with my bench power supply, the current switches between 20mA and 0 every second. I can also hear a very faint ticking sound coming from the board. The APU remains cold.

If I apply 0.8v onto any of the coils above the APU, I get a current draw of 410mA, but again the APU remains cold.