The sunroof of the W202 and W210 are totally different from the former W201 and W124 sunroofs.
The 1993 and 1994 300E/E320 had the sunroof motor in the trunk and the W202 has the motor just above the front courtesy light.
If you take away the left reflector/diffuser of the front courtesy light, you should see an allen/alen/alien (I don't know how you call the "imbuss") bolt that belongs to the axle of the sunroof motor. You can manual control this axle and you should be able to manual pull back the sunroof. Give it a try to determine whether the sunroof itself functions properly (so you can see whether the problem is to be found in the switch or not).
with a minor 600+k