The plug is kind of hard to see - seems like it was about 1/4 way up the wall from the floor.
To quote Witchen's wt
"You will find yourself outside the door to Ozgar's domain. Don't go clear up to the door. Instead turn right and look at the communication units (yellow lights) in the alcove off to your right. See the rod the communicaton unit is mounted on? Follow it down to the floor to see the plug."
Dark Side : Risen
I can only please one person a day. Today isn't your day. Tomorrow's not looking good either.