Well I got a 2002 S55 and this morning I tried to start the car and the key wont even turn onto the the 1 or 2 position. I only got one key so I cant find out if its a bad key. So maybe i though it was a low car battery. I hooked up the jumping cables and the key turned. The battery isnt low cause I disconnect the jumping cables and i turn off the car and it stared like normal. But then I turn if off a 2nd time and the key wont turn again.. What could be the problem?? The battery is about 6 months old and the I replace the key batteries like a month ago also.