The 215 vehicles with chassis numbers lower than 004585 have this defect ABC controller. I have document # GI32.50P-003670, but it is in Swedish, and the number may not be traceable in the US.
You will need a clamp-on mA-meter that can be clamped around the negative GND cable of the battery. There are instruments on the market that can measure DC-currents down to 10 mA full scale deflection.
The methode of checking it is basically to measure the battery current for a period of a few minutes after the car is turned off (after a ride). I did this with the rear lid open (but lock forced-locked by flipping the lock in lock position thus fooling the car to think the lid is closed).
First, check for current drain after locking the car within 60 seconds. Wait for a few minutes to verify system shut-down, as all modules enters sleep-mode.
Then unlock, start the engine and repeat the procedure, but this time wait for some 120 seconds after engine-off before locking and monitor the current consumption. Initially, it is quite high, several amperes, but as system after system enters sleep mode, a correctly working vehicle electronic system quiescent current should be barely readable (there will be some flickering of the mA-meter)
If the current in this second test after a few minutes still is in the range of 350 mA - you have a defect ABC-controller.
The bad thing: It is expenceive, in the amount of $2200.
The good thing: Mercedes has appearently upgraded the chassis response algorithms. After the change you will think you've got four new struts. The chassis response improvement is remarkable.
I advice to have the workshop verify the diagnose before ordering a new controller (if you think it is worth it).
You will need to make the controller replacement at a workshop equipped with StarDiagnose, as the vehicles' position sensor values needs to be read and programmed into the controller.