Hard to say after only a few hours.
Is he warm enough?
Your substrate, and possibly enclosure, looks too dry for a baby leopard. Humidity should be 80% st all times. Your enclosure looks open topped?
From Tom's Leopard Guide:
"Maintaining a small open topped box at 80 degrees with 80% humidity in a regular sized room that is 70 degrees and 20% humidity is VERY difficult, if not impossible in a practical sense. A closed chamber makes it easy"
Without optimal conditions, your tort's shell may pyramid, he can/will dehydrate, and he will likely not exhibit a comfortable routine of regular tort behavior of eating, sleeping, basking, exploring.
Optimal conditions will give you the best shot at optimal health. Get those tweaked properly and I would bet he becomes more active.
The turtle does indeed freeze when they hear and see you coming. They aren't entirely used to you or the human traffic near their box. The way the turtle probably sees it that there's a large mammal approaching them and they might get eaten if spotted so they freeze. They probably think if they stand still you can't spot them. This behavior is normal animal behavior that I think you can only correct over time by letting them feel safe and make their life more stress free by having the turtle in low human traffic/noise area, only interacting with the turtle gently and infrequently until they trust you as the person who doesn't hurt them and feeds them. No fast movements around the turtle etc. Plastic reptile safe fake plants are good way to make the enclosure look prettier and have the turtle something to hide under to feel more hidden.
Look up the care guides in the stickies for good information on how to improve your enclosure and care, also there seems to be mold in the lower left quad of the image in the substrate.