Oh what a tough call. I would say that if its been more then twentyfour hours you could try chiping a little of the shell away at the pip area and see how he is doing in there do tiny bits at a time and stuff if there is any blood. I hope someone that knows more will have more information for you soon.
You may have to help her hatch. Use blunt tweezers and carefully zip open the shell. If you see blood, stop and wait an hour before continuing. Check and see if she's still connected to the inside of the shell and if she'd absorbed the yolk sac. If there's no blood, the yolk absorbed and everything looks fine she can come out.
Good luck and keep us posted!
I waited 4 more hours, it tried to zip but was so cockeyed in the egg she never would have gotten out. I carefully peeled her out--membrane was very soft and pliable, not a drop of blood--after I got her head free and upper body I let her finish kicking out. Crossing my fingers she'll be okay.