Ok, so i was dring my 87 740 w/ bosch L jet to go to a store and it just died on me. This had happened before, and i found it to be the radio suppression relay thanks to the 700/900 FAQ. Wasn't too worried, called up my friend who owns a 7 to borrow a relay so i could just drive it back to my house and resolder the thing. No go. Swapped in 2 different rsrelays, and car would not start, so towed it back home w/ another friend and decided to work on it later. Then the first friend calls me saying her car isn't running. Go down there, they'd reinstalled the relays right, but car (92 740, w/ regina... correct me if i'm wrong) would not start. Swapped the two relays, no go. Battery was low so we threw an emergency jump pack on it, cranked strong still no go. Frustrated (her at me and me at the car) went back home to try and fix mine. Resoldered once, threw back in, no go. Decided to swap relay w/ one from my sisters, an 88. Car fires right up. Resolder my original relay again, car works.
Is it possible that i reset some switch in the computer by throwing in a perfectly good working one? Any ideas? The more info the better, especially if there's something i'm looking over on the Regina system, it's still sitting in her driveway and i feel like sh*t because of it. Is there something aside from the relays i should be looking for?

I'm getting very discouraged w/ the 700 series in general, starting to think of going back to a 200. Any opinions on that as well?

Sorry this was so long, thanks in advance!