Myst 3: Exile Walkthrough
Voltaic: The Lava
Part 2 involves the lava room. Back from the very starting area, go straight into the giant chamber. You go up and across the very top spine into a hatch. You're looking into a room. Head down and actually enter that room. You want to turn a fan on that's blocked right now. Do combinations of sliding and rotating to get the platform to move.
Once you can see the fan, turn it on. Note the interseting drawing in the room :) Now you want to rotate things to let the lava back in. You of course have to let the lava actually into the room from upstairs ;) You'll be able to tell that because the room lights up again from the lava glow, and when you go down to the door again you'll see the lava in there.
The Myst 3: Exile Walkthrough