need help car wont start

[9838stang]

Was cleaning the car with the radio on, i finished up and went to put car in garage. Turn the key and click. car wont start. i checked the car terminals, took em off cleaned em reconnected the battery, click. i noticed the theft light would blink once when i turned the key back to off. When i had my door open, and tried to turn the car on the dome light would flash on and off repeatedly. i also noticed that when the key is in on, i can move the auto through gears with out touching the brake.... i hooked up my aunts explorer, thought it was possibly bad battery, waited a bit and turned the key and click.
tried charging battery battery is only 1.5 years old. still nothing, swapped my battery from my car, to the battery from my uncles truck. still nothing. put battery back in uncles truck and it starts right up.
i do not have another key to try to see if the pats is working or not. but i routed a ground wire from the battery (neg) to a bolt that hold the alternator to the bracket and the car started right up. im thinking i just bypassed the system though... once i take the wire off, the same problem occurs.

 

[robb15033]

I got stuck yesterday for 2.5 hours with a dead battery. During the time I took off the battery terminal wire leads to clean them up, the battery got enough juice back to crank over.
It was the negative battery terminal with a slightly corrosive look to the cooper.