THese levers work. You only have to click them once (they dont make a sound). They are used to open the way to the demon.
It seems like the game thinks you're in a cut scene. Try reloading to a fase before that (if possible).
btw: what version are you playing? There is a known bug with the demon if you use scorpions and freeze on him to defeat him. He dies and nothing happens. This was fixed with the latest patch. But if i understand it right, than you can even start to fight him right?
