I guess you need a sufficient key card? I started a new game cuz the old one just bugged stuck with everything with no fuel around. And it turns out it can show you primary objectives into areas behind you that you can't even access yet, due to the keycard issue. If you go through the low left part of the map (through the red square area I painted in my previous pic) you should get the keycard somewhere along that route.
Also the whole "not enough power" thing closing off previously opened elevators and doors is a bug. Apparently like many other things, the game likes to randomly forget that you ever activated generators when loading a save. So you just randomly have to run through the entire hecking map all over again and hope it doesn't happen again.
