my pac man recently died too. He was estivating, and I guess he just got to stressed out from me checking up on him to make sure he was still alive. I was really depressed; he was so beautiful and he was named Bubba. But even your frog was estivating, he would move if you did something, so most likely your frog is dead if you can turn him on his back and he does nothing. Have you been moving him around alot, or checking up on him alot?