It sounds like you're doing everything right and that he's hungry. Maybe you just need to try pre-scenting the room to get him into feeding mode?
I usually do this by thawing out the prey and then warming it up with a hair dryer in the same room as the tank, because it really releases the scent well. My bp has never gone off feed, but ever since I started warming the mice up with the hair dryer, he goes berzerk about his food.
Let me know how he does!