Another thing is that you cant just put it in there sometimes a ball python needs some movement to trigger a feeding response. I would try some tongs or some hemastats and dangle the mouse around in front of you snake and he should go after it. If he dont go for it with in 5 minutes you could be safe in assuming that he wont. Then you put it in a ziploc bag and get as much air as you can out of the bag and put it in the freezer. I had to do this with a rat with Jojo, he refused his first meal ever and i just threw the rat away. The following week i tried again and no go well he shed the day after then i thawed the rat and he took it with no problems.