Just a quick update. Had to remove a false panel to get to it, but I found the converter in one of the basement compartments. 120VAC in, 0VDC out, fuses good. Battery at 4.X volts (probably going to need a new battery). New converter on order, should arrive tomorrow (monday). I will post back when there is more to update.
Thanks to everyone for their input. I was unaware that some ceiling lights in RVs could be 120VAC. When I saw the light worked, and a 120VAC plug worked, it seemed that at least part of the RV had AC and part DC power. Now I know the DC was totally dead...and it just had AC. I am guessing the electrician fried the converter (or it went bad about the same time), and it worked "for a couple months afterward" because the battery had a charge on it...once it discharged, it no longer worked.