You may try and manually open the sunroof. To do this, flip down the cover on the left inside of the trunk. Insert the socket wrentch (from the MB toolkit - if available) through the access hole in the panel and place it on the hex-drive of the electric motor. Turn the socket wrench carefully. To open the roof - turn counterclockwise; to close the roof - turn clockwise. I don't think your model has the roof that raises so the above information should be OK.

Hope this helps.

-Stephen Davis
1988 300E 90k miles
MBCA - N. Texas Section