Stewart_Reptiles hit the important stuff.
I would weigh him an keep track of it. What's your location? As, if your in a cold belt having a Ball slowdown is more the norm even if your husbandry is perfect. If he starts losing weight (1/4-1/3) then it's time to try the tricks.
Tricks
Scenting the cage. Thawing the prey out on top or near the snakes home.
Offer smaller prey.
"If" you try live. An "if" is the snake is big enough. A live rat crawler is safe to leave in the cage for an hour or more. Some will say the same about a weaned rat, I'd watch them.
Search the forum as I haven't covered 1%.
Then you have live baby fowl an birds.
Or my favorite ASF (African Soft Fur). Since I started raising them I don't get snakes going on strike. Something about a smelly male ASF just makes the snake hungry.
Good luck an keep us updated.