This has happened before, so don't feel too bad. The battery post positions are actually reversed in my 1994 Capri vs. my 93, go figure!!! I assumed you checked the other under the hood fuses and they are all good.
I bought a dead Capri with a history of reversed battery leads, the 80 amp fuse was bad as well as needed another ECU (computer). I see used ones for about $50 occasionally. There are 2 types, one for NA and another for XR2.
I'm not sure how to conclusively test to see if the ECU is bad, lots of diagnostics rely on it giving a good signal, so other bad test results could be misleading. It's under the dash, down low in the center, not 2 bad to get to, having a double-jointed back helps...Chris
