medusa is a PIA to do a swap on. Those staples in the side rails are horrible. Whoever thought that was a good idea at bally, needs a kick in the crotch.

the first picture looks like a toddler soldered that diode. I'd redo that first and make sure you have nice connections. If there are other solder jobs that look like that, you might have splatter in places that is arching on you.