I’d guess fids isn’t going to be able to access diagnostics when he’s got no lights or display 🙁 .
Fids, have you meggered / disconnected individual components to see if there is any change in the machine’s behaviour?
Have you examined board / boards for visible damage?
Have you tried squeezing / tightening and wiggling connector blocks?
I wouldn’t want to encourage any unsafe practices of course, but if you do this with the power on and with a wooden stick you may be able to find a loose contact. 😯
Mike.