Its a 1994 Toyota Hilux Surf SSR-X and I accidentally exchanged the positive terminal with the negative terminal and now the whole electrical system is down. Nothing happens when I put the key on 'ON', neither nothing shows up on the clock and the stereo doesn't work. The only thing that works is the lights on the door that indicate an open door and the beeping sound telling me that a key is in the ignition. What exactly happens when you exchange the terminals? What should I check for?