I would try:

(1) Scenting with a live animal if possible to get things going

(2) Feeding two smaller prey items, one live and one dead. Feed the live one first and get him excited, then right after try giving him the dead one.

(3) Try feeding with the lights off

(4) Try thawing and heating up the prey item then leaving it in his warm hide overnight.

I have gotten several picky eaters to switch over using the above or combinations of them.