Ia m also stuck here.
did the room that changes with the lever, than moved to the room with the pressure plate that pops up for another battery cell, than grabbed the cell out of the shockwave room.
I even did the upstairs room (top left on the map) lever
Now I am stuck since i only have 2 cells (need 3 for the main hall door) i cant seem to do anything in tiami room
SOLVED: its that kitten mirror, or what i thought was a mirror