I've made it as far as the sewers monitor room and have done the following:
Finished the chess puzzle to unlock the door. Played the video tape about the rats spreading the virus. Collected all the stuff that I can see from the room. Defeated the nasty dude and rescued Ada. So I'm back in the room about to leave to the darker depths of the facility.
But, the room is still red:
The two ! in the image are:
Video Player and Plug Socket, which I've already done. Unless there are more videos to play?
Am I missing something later in game where I need to come back?