There is an elevator shortly after you get into the main part of the temple (after you kill the guy who calls you a heretic). There is a button that calls the elevator, and it takes you to a small room with a couple of barrels and a chest. I got up there, opened the chest, and now the elevator won't take me back. HELP!!!! How do I get out?

After the monkey chute room and near the 6-door puzzle storerooms, right? I had the same problem - couldn't get out. In the end, I loaded an earlier save and skipped the room since the chest didn't have anything important.

I posted a big piece on Buggy Lift Syndrome, possibly titled D'Soto's lift. Anyway, the common thread is that some lifts stop functioning, particularly if a monster strolls by where you got on, just after you used the lift to get somewhere. Always save if you're about to go on a lift ride is pretty good advice for Serpent temple and Shurugeon castle anyway. Suspect you are going to have to reload.