The Dink Network

I am at the cave with the plaque that shows dancers and one of them flipping a switch. There is alot of stuff behind a locked doorway next to the plaque. How do I get in it? I thought the plaque ment I had to flip a switch, but I can't find one anywhere. Please help, I am completely stuck.

In one of the caves there are 4 pillars with snakes - one is different