last months i changed oil of my Cadillac DTS 2007.then I re set. but next morning it did not start then I connected my other car's battery to Cadillac DTS 2007's battery with jumper.after that Cadillac started. then my mechanic suggest me to changed the battery and i did. day before yesterday i did oil changed again and reset. but again same problem happened. this time my mechanic saying that there is no prob with battery. but why when i charge the battery its getting start. i can understand whats wrong with my car.pls help me.