After a LOT of attempts I managed to descend without cheating, there only one way to survive and is very unreliable and RNGish:
Activate the elevator, when the cutscene of faceless appearing ends inmediatly hide on the pile of boxes, the elevator has a counter of 6 until arrives, it should be on minimum 4 before the faceless spots you, after that manually initiate combat and pop every defensive element at your disposal (morphine, shields, cloaking device), you must withstand 2 turns and the elevator appears (This cause a encounter reset; if you have low initiative it can be bothersome) finally rush to it.
Depending on your build, my character survived thanks to only one mindreader appearing in one attempt and of course NOT BLOCKING the only path once they spot you behind the boxes.
Good luck and patience for those hunting the fabled Mind Cracker.