Deceased for unknown reason. First two photos are in situ. I returned the turtle to its resting place after taking the plastron photo.

Based on odor, and the fact that a toe broke off when I moved it, this turtle had been dead for a few days at least. At least one more is in the area, as fresh tracks from another Blanding's Turtle led away from this spot:
https://www.inaturalist.org/observations/54355705