Does he open his mouth to bite when you mess with him? You can hold a bite of food, worm, etc. in the tweezers and when he opens his mouth, drop it in.
Sometimes if you feed them in a smaller container they can find the food on their own.
I'm trying to remember...we had a member here who went through the same thing with a water turtle. I'll try to find the thread for you.
Here it is (I LOVE that GOOGLE custom search square at the top of the page):
Keep him in a half inch of water for several weeks until he eats regularly then slowly increase the depth of the water. But I would never go over 2-3 inches with a blind turtle
He has no eye sockets at all on his head, he does eat but he waits lol i tried feedin him in shallow water but he panics he just loves his chillin on bogwood