Yikes. Just chiming in, but the MPU board has some burned components in the lower left hand corner that may be dragging the voltages down. Also, that header on the MPU needs replaced, as do the pins for the connector that goes there.
As far as the power supply board, it needs connectors replaced and the board pins replaced, too.
There’s a note on the MPU saying it does not score properly, so this board had issues before you got it.
I recommend going thru this systematically, as has been suggested previously.
Good luck - I’ve brought back boards that were in worse shape than these.