You have to go around the other side to enter the elevator.
That's not this case, I'm afraid. Several players reported that after returning and completing "heist" part of the chain they can not get further directions from Dodona (which is opener for Belsavis). As they find themselves outside and can not enter instance, and it turns red.
Well, at least that's how I got this problem, something about this mission was described in several threads recently.