I brought my car into the shop at school to put on a new suspension. This was on Monday. I left my key in the ignition, turned all the way to the left on lock. This afternoon (Wednsday) I finished the suspension and put the car on the ground and I went to start the car and it wouldn't start. I cleaned the negative battery post and tightened the clamp on the negative cable and the car started. Then I shut it off and it wont start again. This ever happen to anybody? Any suggestions on what to do?