Has he been handled at all since you brought him home? If the answer is yes, then stop handling him, and try again after he's been left alone for a week. I would recommend trying an appropriately-sized live rat. Some ball pythons prefer rats, and some prefer mice, in my experience. Since you aren't sure what he's used to, if he won't take one, then try the other. Also, try feeding him about an hour after lights out.