I'm having problems with this quest, and specifically with this location, Nchardak. I had already talked with the Telvanni wizard Neloth about the location of the Black Book at Nchardak. He had led me down to the ruin, and there we killed all of the Reavers before the door. It was here where he took his cube and placed it into the door mechanism, opening the door. We both entered, and I listened to his speech about how we need to get the steam rolling again. He went over to the elevator and went into the next area. It was at this point that I realized that I was a couple pounds from being over-encumbered, so I left the ruin, left Solstheim, and returned to my Hearthfire home in Falkreath. After storing all of my materials and whatnot, I returned to Solstheim, and promptly returned to the ruin. I approached the gate to Nchardak, the same gate opened by Neloth with his cube. I cannot find any way to open the door myself. When I move the cursor over the door, simply no activation prompt comes up to open the door, and trying to manipulate the door mechanism lead to a message along the lines of "You lack the required item". The quest marker still points to the door that I cannot open.

This is because Neloth still has that cube. A little later on he will give the cube to you.

Yes, but how am I supposed to get the cube from him if he's inside the ruin and I can't get in without the cube?

Try checking in the tower. He might have gone home.

You cannot. You have to go back to an earlier save. Sorry to say.

Oh yes, I forgot to mention that as well. I returned to his apprentice at the tower (after searching for Neloth himself there), who told me that his master had gone off to Raven Rock to do some research. I searched all around the area of Raven Rock, and I couldn't find him anywhere.

stupid ass bug. I just cant believe after two days the game has found many gamebreaking bugs. Try checking in the tower. Or reload. Im not sure.

Well. There goes my game I started two weeks ago in preparation for this add-on. No saves that are even close to before I went into the ruin. I don't fast travel, and I save a lot, so my closest save is on the way back to the ruin after leaving to store my things.

I am sorry. Do you have a save inside the ruin?

Nope. That closest save I was talking about was about 3 hours after I left the ruin. As I said, I save often, and keep about three different saves that I override in order.

Sorry to hear that. I do not know of another way.

It's alright. Thanks for the input though.