Nothing. Mine's an '05 and I had the same problem in '08. It turned out to be the SKREEM (alarm) module. But my Panic button wouldn't work either.

They (MB) changed the SKREEM unit, at least the part number, in the intervening years. I think that cars '07 and newer have the new part number.

And my battery went bad, slowly, with the "spoiler auto-up" syndrome.

A little paranoid are we?