Try f/t: if not off tongs then see if leaving it in with him overnight does the trick. I like to leave it right outside the entrance of the hide when the snake is in the hide so they can't miss it.

He may not be eating because he's in a more open cage over the tub you think he was in with the previous owner. Really clutter up the cage and black out three sides of it and see if that helps. If not, I may set him back up into a tub.