Have you been trying to feed the corn snake f/t or live?
How are you going about it?

Some of my hatchlings actually seem to prefer f/t. 2/8 didn't eat their first meal (live), but 8/8 ate their second (f/t).
If I have a picky eater, I will put an f/t pinkie in a small plastic dish w/lid. Chances are, you got him in one similar to the ones I've been using. I put them in there with the mouse and leave it overnight. If that doesn't work, try braining the pinky.

For the ball, I think lowering the cage size to a 15q and raising the temperatures a bit will do the trick. I usually have my flexwatt temps at around 100F in order to get a proper in-cage temperature. Good luck!