One day I went out and my 2000 Grand Prix would not start. It would roll over constantly but would not fire and run. Instinctively I changed the plugs on it, which I found out were factory original and had 235k miles on them. Now It runs fine but it requires being jumped to start. When I go to start it all the lights come on, the dingers ding and I can hear the fuel pump run but when I turn the key everything dies. The lights turn off and it acts like it has no power at all. When I let go of the key the lights come back on. If I hook it up to another car with jumper cables it starts right up no problem and will run just fine. The only thing I have noticed is after I run it for a while a little bit of white smoke that kind of smells like burning rubber coming out from around the middle, front spark plug. Is this just a bad battery or something worse? And what could the white smoke be and how could I go about fixing it?