I'd just let him be. If he dies open him up then and look at the stuff left in the shell. You will see the yolk sac if it is still unabsorbed. It will help you understand the process if you look at the unhatched or dead in the shell chicks. If you have eggs that stopped developing at different times in the process (early quitter, late quitter, pipped and died, never pipped, but dead in the shell....) you can begin to troubleshoot the causes.
Here is the link to the info I mentioned earlier: https://www.backyardchickens.com/forum/viewtopic.php?id=48726
Good luck! Let us know how the rest of your hatch goes. Don't be discouraged!
Here is the link to the info I mentioned earlier: https://www.backyardchickens.com/forum/viewtopic.php?id=48726
Good luck! Let us know how the rest of your hatch goes. Don't be discouraged!