The 2010 Buick Lacrosse’s battery location is under the hood, just like in most cars. It can be easy to miss, though, since it’s underneath a plastic cover. You’ll see the battery (and its cover) toward the front of the engine bay, on the driver’s side. Its cover, which has a plus and a minus sign on it, should pop right off with a little bit of pressure!
I’m sorry to hear you’ve been struggling with this issue. Hopefully, now, you’ll be able to find the battery location for your 2010 Buick Lacrosse without any more trouble.