91 Civic Won't Run

My '91 Civic wagon's horn doesn't work. I tried to fix it by replacing the fuse. The new fuse blew immediately. So I traced the wiring and found corroded and broken wiring at the horn. I fixed the wires but the fuse still blew. I took the steering wheel off to see if there was something in the horn switch. This car is old and there is nothing electronic at the steering wheel except the horn (i.e. no airbag, no cruise control, etc.). I touched the copper clockspring to the metal steering wheel hub thinking this would "complete the circuit" and would either sound the horn or blow the horn fuse again. But instead I heard a some beeping from within the car, not the horn, but more like a warning beep, like when the lights are left on or something. Then the car wouldn't start, and there seemed to be no power (no radio, etc.) However, when I turn the key off, there is a fast loud clicking coming from some sort of device located near the floor in the center of the car, very close to the heater vent. When I turn the key back on, the noise stops, but car remains dead. Any ideas?