As I stated before there are two seperate transmitters in the remote. The lock unlock is powered bt the batteries and is infra red and rf (radio frequency)
The start and steering unlock is handled by the chip in the remote that communicates to the body computer and draws its energy from the collar via inductive energy, it sends a signal back to to the engine computer which will verify the code and unlock the steerig wheel lock and the key lock, this will allow the key to turn and is redundant. the data is also sent to the engine control module which will allow it to start. I suggest you let MB have it, and use their diagnostic tools.
The computer is powered by circuit 15, I hope you have not removed any fuses