OK. You said that the solenoid kicks one time and then nothing. Next, try a KNOWN good battery out of another car and see what happens. It's possible for a battery to show 12 volts but have a shorted cell (and will turn a starter without a load on it). That's why a 'battery load test' is a good idea. At any rate if another battery cranks the motor we'll know. I also recommend removing the ground cables (bat. to engine, and engine to frame/firewall) and brightening up the contact faces to insure good grounds. If a different battery gives you the same results, try to hand crank the motor with a socket on the balancer bolt. You want to make sure the motor is free to turn. Hang in there!!!