You need to start with the basics like checking all of the fuses.
There are 3 spots for fuses in this car. One is the main fuse box under the hood. One is the base module in the module box. One is the rear fuse holder in the trunk.
Be sure to check them all.
After that, work the roll bar and make sure that it is all of the way down or up before trying anything else.
ASE CERTIFIED MASTER AUTO TECHNICIAN
MERCEDES SPECIALIST 11 YRS