I can't tell you what to do but I'll tell you what happened to my 90 300E. The trunk key was stuck in some strange postition and I could not use the key or the vacumn system to open the trunk. The door locking system continued to work fine but I could not get the damn trunk open after trying virtually everything. Finally, I took it to the Mercedes dealership and they drilled out the tumbler, replaced it with a new one, matched it to the key set, gave me an extra key and it cost me a few hundred dollars.