i'm not sure what the issue is then. An initial problem characterized by bad ROM data (not uncommon in old ROM chips) or faulty a ROM connection (quite common with old boards) was exasperated by removing and putting one in backwards...this ALWAYS kills the chip because of how the chip power is pinned out.
the thing to do is fix the known blown chip and go from there.
if you want to be sure, just order a whole gorf replacement ROM set and change them all. dollars to donuts if you did that, it would work just fine.
there is no "repair" involved here unless you have traces burned off the board or you stepped on it and broke the board. ROM chips are meant to be replaced (game updates, fixes, etc.) it's easy as long as you don't put one in backwards (as you've learned already) or mix them up...which usually isn't fatal, it just doesn't work.
If you are looking for someone to just do it for you, find a repair service such as "Mikesarcade", "irepairsega" or "Arcade Services" and ship it to them and have them fix it for you and send it back.