Today I tried to install a new battery and after connecting to the + terminal I fumbled around getting the - one on. This set off the anti theft alarm and the horn wouldnt stop I tried putting the key in the door but this didnt help. Finally I just disconnected the horn. I hooked the battery up and got in the car and tried to start the engine. The only thing that started was the fan and some of the lights on the dash came on. I dont know what the hell is going on, but any help would be greatly appreciated.