I also had the mysterious dead battery about three weeks after I took delivery of my new car. I think it was manufactured in May, 2010..[/size
Anyway - they towed the car into the garage, did all the tests, and nothing showed up. Then I took a trip and my tailgate locked up. Then the motor in the tallgate died. Since then, my battery has worked fine.
At the time, they told me there were no service bulletins. I had taken my car through a car wash prior to the first incident. Dealership said that they had also water -tested and showed no problem.
I had the same battery issue with my Ford 500 and they finally decided it was the radio.