I'd help him hatch. You'll have to go slow, to make sure you don't burst a blood vessel. There are detailed instructions somewhere in here on helping a hatch (not sure where--try a search on the forums or maybe someone will post the link--), but the basics are that you take it out, use a pair of tweezers and gently but firmly start breaking a line around the cap the way the baby would do, always pressing from the inside of the shell (because the pressure on the inside of the shell is what tells the membrane to stop circulating blood to that part of the membrane). If you see bright red blood, stop and put it somewhere good and warm (like under a brood lamp) for 15-20 minutes. Small amounts of dark red liquid are normal. When you are done, you can let it pop itself out of the shell. Put it under a brood lamp to keep it good and warm, then pop it under the momma hen at night.
Good luck!
