My husband left a light on in our car. Battery died. He went to jump start it and hooked it up wrong or something...smoke started. Took the battery out. It was swollen so we bought a new battery. My brother (who is mechanically inclined) put it in and the car started right away (to his surprise). He was sure some fuses were blown but it ran. He then unhooked the battery with the car running and the car shut off. He said that the alternator should be replaced but I also heard that some cars have to have the battery attached to run. Anyone know which way it is for the 2006 G6? I don't want to order the alternator unless I really have to. Thanks. Any info helps.