You might have to force feed. It isn't too difficult if you choose the right size food. I have a non-feeder hatchling who I have been force-feeding for four months.
Buy a pinkie that is smaller than you would normally feed him and then try this method:
Place a large towel in front of you as a work surface. While holding the snake directly behind the jaw so you have control of his head, gently pry his mouth open with the tip of a toothpick. Once you have his mouth open, lay the toothpick across his jaw (like a dog holding a bone) to prevent him closing his mouth. Pick up the warm pinkie. Slide the toothpick out the side of his mouth while placing the pinkie in from the front, nose pointing toward the throat. Gently push the pinkie into his throat, nose first so the throat opens easily. If the pinkie is small enough, you can usually get the head of the pinkie all the way into his throat. Push the remainder of the pinkie into his throat. I use a rounded stainless steel rod to do this, but use whatever you have that is smaller than his neck and has no sharp edges or points to hurt him. You'll know you've pushed it in far enough if you can close his mouth. He may try to regurge at this point, so it's important to hold him a little while to make sure the pinkie is going down and not back up. With my little guy, I gently stroke his throat until I see the lump completely clear the throat. If he tries to regurge at this point, I push the pinkie back in and gently hold his mouth closed. It's very scary the first time, but you'll know he has some food in his system. He may return to feeding on his own after being forced once or twice.
Good luck.