Not sure if you still need info or not, but on the occasion when I have had a chick hatch this way, I place a moist wash cloth in a cup or bowl. I then lay the chick on top and place the cup/bowl back in the bator. I do check on the chick every few hours and change it's position so that it does not develop bed sores or the yolk sack does not stick. It can take any where from a few hours to a couple of days for it to reabsorb. My chicks never make an attempt to stand while the yolk sack is still present. At this point you do not need to worry about food or water for the chick. They are still getting nutrition from the yolk. Once the yolk is gone, I would leave him separated for a short time longer from the other chicks. When you do remove him from the bator you may want to give him some Pedialyte. Dip his beak in it but be sure that you are not submerging it and getting it in his nostrils. Give him some time. Most of mine have turned out fine. Good luck.