A lot of times, what happens is that the negative lead will work itself free if the compression nut isn't installed correctly or something is placed in between it and the clamp like an accessory ring terminal. This will make it so that your dash lights up and will even kill your motor. The process of hooking jumper cables to the battery alone is sometimes enough to give the pressure needed to the terminal to start the Jeep and that gives the false impression that the battery was dead.
