Horn not working on Buick Century Custom?

Somebody tried to steal my front grill one night and it set the factory alarm off. After a few hours of honking, my neighbor across the street came over @ 2am to let me know my alarm was going off. I tried to reset it with the remote, but I had to disconnect the battery to stop the horn. I checked the fuse, which was good, and swapped the horn relay with a known good relay (a/c clutch), but still the horn is not working. Got a horn off a junkyard Camaro, installed it and still no horn.