you can go to a local pet store, ask for wood shavings from a gerbil cage. Lets your mouse sit in a bag of these after thawing for awhile, the scent of the gerbil(ball pythons eat gerbils in their native environments) may be enough to trigger a feeding response. Make sure you warm its head with a heat lamp or a blow dryer afterward. you can try also putting him in a smaller, darker enclosure with the mouse to give him more security. i'd say put the gerbils-scented substrate into this container as well, but be weary as they could be pine or cedar shavings, and those are toxic!