macdaddy6

Hoping for some help. I went outside yesterday and heard this weird rapping/popping sound and it was coming from my 1997 Lexus Ls400. The car ran fine the day before and was sat overnight. the rap or metalic pop was coming from the engine. I tried to start but the battery was dead. I went to jump it and when I connect the jumper cables the car tried to start by itself with no key in it. I put the key in it and tried to get it going but it was racing and dieing so I took the key out and unhooked the battery cable. The rapping stopped and the car is sitting there. Any thoughts ??