Hi Pete! no worries, these are about the easiest board there is to repair. Especially if the Fets are still good. There is an EGS002 board on it with a socket. Id recommend just replacing it. I got 5 for $30. Individually they can be had for $8.00 when you get the new one find a magnifyer glass and make sure the jumpers are set to your liking. Frequency 50/60 dead time etc, just copy jumper settings from your old board. I will see if i can send manual.
Then make sure fets and caps are good, you already did.
Next there is a tiny 24 to 12v 3 pin buck regulator board near the edge. You will need to make sure it works. The pins should be labeled. Vout, gnd, vin.
I would remove the egs002 board, apply power to board through a fuse or small wire and then verify 12v, if thats good and the tiny relay clicks and green light turns on then all you have left is plug in the new egs002 board and away you go. If tiny relay doesnt work, then the housekeeping chip got hurt, its an LM324 quad comparator i think, two options, replace it or just tie your on/off circuit to the tiny relay coil (observe polarity, there is a diode across it. You can get 12v to power it from the tiny converter. If the tiny 12v converter is hurt you could just get a new one of those too or your own 12v supply. If you wanted to fix the egs002 board it could be done but not likely worth it. Pretty much just replace the driver ics and 8010. If you think the FETs are perfect yet id be really careful about using/repairing the egs002. A wounded egs002 could wipe out those fets quickly. As cheap as those 002 boards are it just makes sense to have a few on hand.
Those boards have virtually no labels on em so maybe grab a sharpie or black marker of your flavor and write +24 on the heat sink Gnd etc.. I can see how that could happen the way they are labeled. The 5500w is fairly accurate as well. I hurt one by letting two grid ties go at it with 5.8kw of incoming power, so maybe keep it to 4500 to be safe. They are better than PJ when it comes to holding the voltage down, if i remember i had it set to 240 v and i think it only rose to 244.
I just reread your post and it is possible the only thing wrong with yours is the lm324 chip. You can remove it and just power the tiny relay on and you might be running. Again, use care by removing caps and supply with resistor or some trick to protect fets id hate to see you loose those now when they are worth more than all the rest of the bits.
Good luck! I believe youll have it running in no time!