I completed the quest and killed Kellogg. I got the key from him and unlocked the doors from his terminal. The doors to the command center opened but if you go up the steps and to the right, the door that leads back to the elevator is closed and I can't find a way to get it open. I even talked to Valentine and told him I would follow him back to Diamond city and he can't go anywhere. He gets to the door and stops and just walks around. How can I get past this. I have gone back to a save prior and replayed it a second time and it is doing the same thing.