Try feeding at midnight, switching off all the lights in the room while you thaw it (and don't switch them on until he takes the rat) and then pre-scent for 30 minutes right before using the hairdryer. Doing this all in the dark is hard, but as long as you know where everything is. This is how I got my new BP to switch from live to f/t, as well as eat for the first time for me! I also found it important to stay hidden behind one of his covered tank walls. You wouldn't want to eat while a giant is looming above you!