This morning my Model S did not recognize either of my keys and wouldn't open the doors although the batteries were relatively new (got the car services about 3 months back and it was supposed to include insertion of new batteries!). Fortunately, through the iPhone app, I was able to "unlock" and "start" without the key. What could have gone wrong? What do I do if there is no internet connection and the app doesn't connect to the car? Has it happened to anyone?