All of mine sit cool side and warm side side w/ there heads resting on top of their hides in S shape and just full length. Head propped up does not mean always R/I. I figure they are like us and move around into different positions.

Sometimes it takes a few trys to switch over from mice to rats. Follow JLC's advice and just try again. Missing a few meals is in no way gonna hurt them.
If temps are good and everything is spot on then he will eat when hungry enough.