Stuck in Citadel after 2 crushing doors

[max killen]

I'm stuck in the Citadel. I am on the first floor. I have successfully passed the 2 doorways that will crush you to death. The last doorway I had to shoot arrows at the lever to activate it, as the lever was on the overside of the doorway. I followed the path around and came to a hallway with one locked door with monsters on the other side. I back tracked the map to the otherside of this area and found a large central area with many monster inside and several locked doors. There appears to be a lever on the other side of the locked doors; but the lever is "obscured". I think I have done just about all the quests and have a bunch of keys; so how do I enter this central area?

[Kreador Freeaxe]

There's a lever next to a dead body. It needs to be flipped.