That is incorrect. There is no dead end. The same bolt that opens the hatch in the red corridor is the bolt that opens the elevator.
Viewing post in Need a Hint?
Ah, that might explain it. Because I'd kept playing the same game where the vents magically opened on their own.
https://itch.io/t/908644/vents-magically-opened
So that's good to know at least, that it's not a dead end. Was because I kept playing on a bugged part (I never opened those vents in the red halls).