How do you change the battery in a Mercedes Benz key?

I have a 2006 E350 and my keyless entry button didn't work this morning. I want to take the key apart and possibly change out the battery. Does anyone know how to do this?How do you change the battery in a Mercedes Benz key?
When you flip the key up(when you open it), you will see two arrows showing you where to put a small screw driver and lift the cover up...

I hope this helpedHow do you change the battery in a Mercedes Benz key?
nothing special. pop the cover off to expose the battery. go to radio shack and match the battery
since you are unsure,contact a mercedes benz dealer