Wait what? A normal rheostat (temp controller) should let you plug the cord for the mat into it. That'sthe only way it works. Do you have any pictures of the setup?

So the hide is not on the cool side? The snake wentover and burrowed becausehe is cold and had no hide there. He just wanted to feel safe and warm. Put a hide there! You should buy a new heat pad for him just to start fresh. Stick foil to the sticky part so you can move it, and attatch it to a light dimmer or rheostat making sure there's room to 'breathe' under the tank.
Don't even bother trying to feed him till he's had a few day in a stable environment. The snake will only eat if ittrusts that it will have it's warmth and security in the cage to properly digest.