You don't want to cut yolk off babies. It takes a lot longer for a couple hours to see any changes where yolk absorption in concerned. I'm talking generally 24 hours or more. At this point, the only option you have is put a damp paper towel in the bottom of a cup and place him in there and back in the bator. If the yolk ruptured, chances of survival are slim. Especially with a full yolk sac. How much bleeding was there when you opened the shell? I'm assuming there was significant bleeding? That can make a very weak chick. How any days past the hatch date was this chick?