Hi, I've managed to locate the serial number of the board I'm trying to repair in the Bios file, its 5CG21225BC, I'm hoping someone can help me here, I think the EC bios may be corrupt...

Sorry about that
HP Elitebook 840 G8
MB - 6050A3426501-MB-A02
I don't have the serial number of the board I'm trying to fix but the original was 5CG2120BGW...

Hi All
I've been repairing this machine and bought a donor board for spares, unfortunately it turns out the original MB has a shorted cpu so is toast.
So now I'm trying to repair the donor, this has all the required voltages, no shorts or physical damage but won't boot, it flashes 5 power lights and the caps lock once, so generic hardware failure.
I've had something similar on another machine and that was bad joints on the EC chip, I've reflowed the EC chip on this board and it's no different.
My working theory is the EC chip bios is corrupted or the EC chip has failed...