Help with hatchling turtle

Hey everyone, I’ve found myself in a bit of a spot recently. While checking on my chickens the other day, I find a hatchling painted turtle wandering around outside the pen in the patch of grass. How it got there, I have no idea, but there it was. I can only imagine it was trying to get to the pond which is around 50 feet away. But that pond is full of frogs, and patrolled by Garter Snakes. It’d be a death sentence to let the turtle go there. I have him currently in a ten gallon tank, but I’ve never taken care of a baby turtle before, and am kind of stumped as to what to feed it. Not knowing what to feed these little guys is one of the reasons why I always buy yearlings. I took a few chunks of the food I give my larger turtles and ground it up into small chunks, but that doesn’t seem to be working. I crumbled up a cricket too, but no luck with that either. What do the breeders here on the list feed their hatchlings?