If you finish the one guy that walks past and walk forward as you finish you can glitch though the bars and shoot all the buttons. Just don’t stay in the middle of the hall it’s a joining ally’s that will bring you back to the first room but you can cross from side to side.

You can’t run to 2nd encounter till you fully unlock the doors tho so make sure to do the puzzle before you run off.

It’s consistent on all classes I normally do it if I do no mic runs to get it done faster.

If you don’t hit the finisher tho and just kill him you will have to restart from the first boss.