Have you talked to the person you got him from about what his feeding schedule was like and what he was being fed before you got him? If you can get him on the same thing they were feeding, that might help.

At 418g, he's way too big for a rat pink and it's possible he refused it because it was so small. I know my bps will do that if they prey is too big or too small. Have you thought to try a live rat pup or just weaned rat? That could get his attention and should elicit a feeding response.