This appears to be a Mexican Mud Turtle (Kinosternon integrum), which is actually native to the OP's hometown. This is obviously not a Terrapene, based on the shape of the carapace, vertebral scutes, various other morphological traits, as well as that fact that it has two plastral hinges, rather than two.
There is no way a Terrapene looked "just" like this turtle. Learn to look at the certain clues, instead of just overall shape or coloration. We are taking about differentiating genera that are VERY different from one another in so many ways.
...and because in the pictures the eyes are very hardened and closed, I'm thinking the sooner you get this turtle into water, the better it will be for him. they live in water, not on land. Please put this turtle either into a pond, or into a tub of water.
Definetly a mud turtle. I'm still unsure of why type but but I can tell you he needs a good conditioning and water. He. Is semi aquatic, needing both land and water.