You may have to feed him live for a short period. I'm facing a similar situation with my blood. He ate the first few frozen/thawed meals I offered but then refused several feeds after that. I eventually copped out and purchased a live mouse for him. Before I fed the live mouse I tried to offer another f/t but it was ignored. Within minutes of Cecil noticing there was something else in his enclosure Lunch was being squeezed. It broke my heart to feed the little mouse I grew attached to him and almost didn't feed him.

My suggestion would be to check your husbandry and make sure everything is right. Leave your blood alone for about a week and offer f/t a few more times. If he still doesn't eat get an appropriate sized mouse and see if he'll take that.

Good luck