This was bugged for me I had the key and couldn't enter the room. What I did was go to the door that looks like a gate the one the ghost runs in and then face the door and then use the tool to travel to the dragon tower and then travel back while pressing foreword and it will put you inside the room one there search the body and get a key exit that room the same way and then the new key will work in the other room and then you can complete the quest.
so basicaly you have to bug it out in order to do it atm. (until they patch it.) well okey
