I have a 2000 jeep grand cherokee, i'm having problems with it starting all the time. The battery has full power. when trying to start there's nothing. When getting ready to tow home i put it in neutral to push it back, i put it back in park and i needed to push a little more. when i turned the key so i could put it in netural again, i turned the key all the way and it started. why would this be happening?