I went to start the car the other day. The doors worked, ignition button lit up but would not start when I pushed ignition. Dash lights worked though. I figured it was the battery because it is over 5 years old. I put a battery tender on it to see if it was low. Seems like as soon as I hooked up the battery tender, I had no power to anything. No doors,ignition or anything. Is there a fuse I could have blown? Is it just the battery?