As the title says, I left my lights on today and when I got off a ten hour shift, my battery was dead as they get. I tried to jump it from a friends car but it wouldn't start, now whenever I turn the key it just clicks. Before you start, I know I'm not supposed to jump a BMW, but there are ways and I know the ways. I did everything right as far as I know, but I'm stuck with my roommate's car until he gets back from L.A. I don't really know much about cars anymore, so I'm kind of in the dark here. I know this isn't the ideal forum for this kind of issue, but I've looked everywhere and car forums aren't usually welcoming to idiots like me. If anyone can help it would be greatly appreciated. Merry Christmas, Happy Hanukkah, Happy Kwanza, or lovely non-denominational winter solstice.