1977 Chevy Caprice 1977 wont start after wrongly jumpstart

I have a 1977 caprice which have a problem. The battery died and I went over to jumpstart. By mistake i connected wrong terminals at the battery .ie connected neg on the side of pos and pos on neg side. But realized and connected correctly. But the car never started again even after installing new battery. There is no power at all at the ignition. Horn and lights work. I tried to connect the ignition straight to the battery and will start though will not stop even after removing key. I have troubles-hooted all fuses and relays under the steering and all are fine. I need help please, where else the problem could be? please help