Yes my advise. First do not take it to the stealership! I would take it to a local European auto repair shop. Or do the repairs yourself. Remember you are riding mostly in an SLK320. Most Chrysler stealerships have gotten rid of the test equipment required to adequately repair our cars and MB won't go near it.
Please note our FOB take two batteries you stack them.
The SKREEM module does have to be programmed to the VIN I do know that. I also know there are some places you can send it off to be repaired. They are listed in a thread on here just search SKREEM.
Every little thing you notice about the car can help us determine what is wrong the more information the better.
After you turn the key to the run position how many times does the engine turn over.
Are you required to disconnect the battery and reconnect the battery and try again for it turn over/start again?
If it does run for how long?
All these answers matter. There are a lot of very good people here and they will do what they can to help you.