It doesn't turn on at all (no lights, no sounds, no fan spin) and when I tried to turn it on with only the critical components (motherboard, power adapter and speakers), I got the same result.
I've also examined the power area on the motherboard, and it seems like 20V is getting delivered to the motherboard just fine.
But I've looked at the motherboard thoroughly, and I couldn't find a single part of it that looked bad.
Is this definitely caused by the motherboard, or could it be an issue with another component like the CPU?
As far as I know for this on Thinkpad, there's a problem with your firmware and try to take a boot firmware from another laptop T430. Reflash it, and let's see if it works. If it not works, then by all mean, there's something wrong in the CPU. Try to change it, and if its not work again, change the motherboard.
for anyone looking for info on a similar issue, my issue ended up being that the motherboard was faulty. Flashing skulls didn't fix it, nor a CPU swap. I had to buy a new motherboard from AliExpress.