Stop holding him.. he probably won't eat right away because all that holding is stressful.

Leave him alone for a week.

Even settled in BPs don't come out of the hide much.. most snakes don't. They are nocturnal, so you see more action at night.

Give him that week to settle in, and even after that don't overdo the handling for awhile.. they tame very easily, so don't worry!

Also, never handle a snake for two days after they eat.