I understand your need for checking him, but as long as he is sitting and has clear eyes, he will be OK. There isn't much you can do if he isn't OK and then dies, I'm sorry to say. Follow the advice on feeding and so on, and you will be doing everything you can to keep him happy. If he dies, you will know it just by looking at him, unless he is completely dug down and covered by substrate. He won't be sitting any more, he will be kind of deflated. No need to poke him if he is sitting up.