Rode an elevator up to a storage room (?) in the serpent's temple. There were a number of barrels and a treasure chest within the room. Cannot activate elevator to ride down although I can hear priests, snakes, etc. Elevator has wooden floor and two sets of chains on the right and left of the elevator compartment. Please help!

Apparently this room is bugged. I (and others) too could find no way to get out, so the solution is to reload an earlier save and skip this room. There's nothing there which is important.

Certain lifts get buggy when monsters are around. Reload, wait a few minutes, set spawn rate to minimal. and try again.