I was running errands in my 2011 focus today and had to shut the car down briefly after about a 30 minute drive. When I got back in the car, literally not more than 2 minutes later, everything was dead. The engine wouldn't turn over, the lights wouldn't turn on, even the doors wouldn't lock. I left the car for about an hour and came back to test the battery (only six months old), which turned out to be fine. I checked back again five or six hours later and the car started up and everything worked normally. I'm stumped! Anyone have any idea what happened?