Blocked in Cheogh

I finished the dark maze part with the ghosts and revenants,walked on a lift.I ended up in a room with 3 doors and a button.I opened the doors and pushed the button.What am I supposed to do next?!

You're playing the first one, right?

There are playthrough videos on youtube.

There's another part to the maze which has an opening to a cell/cage with the yellow key.

DoomHero85 said:

There's another part to the maze which has an opening to a cell/cage with the yellow key.

Thank you very much.