Your snake may not be eating because he doesn't feel secure in the tank, or your temps/humidity is off, which is causing stress.
The first thing I would do is:

1) Make sure you have 2 identical, snug hides. One on each end and the water bowl in the middle. This will give him a way to thermoregulate without having to choose security over comfort.

2) cover 3 sides of the enclosure with something like construction paper, poster board, colored foam board, aquarium backing. Anything to make the tank feel smaller, more secure, and not so open.

3) cover most of the top with something like Aluminum foil, or foil tape. This will keep your humidity up. I cut pieces of cardboard and wrapped them in foil, making little panels that I could lay on the screen, then just add or take them away depending on the humidity.

What is your heating set up and how are you monitoring it and controlling it?