I would maybe try feeding him a hopper mouse and see what happens. Once he starts feeding you shouldn't have much of an issue.

I keep my neonates in a 6qt container in a rack with the heat tape set at 85F with no hide. I have also had three neonates, this season, that didn't eat for the first 5 week of life although all the tubs are the same.

Also as a side note, for any future snakes try to make sure it has had a few meals and is feeding well, that way you should have less issues with feeding.