ProgenitorHK47

I've used the 'whereamI armband' to open that door, when it stopped loading it dropped me of in this pitch black place that I could not move around in.

No it isn't, and here are the reasons. 1. That corpse stills has both it's arms. 2. It has no eyes. 3. It's not in a pool of it's own blood. 4. It doesn't look like Atton. 5. It looks pretty rotten, so I'd say he was killed before you get to the Trayus Academy.