I would take a tiny bit of the white shell off and see if the veins are still red and noticable on the membrane. If you see red veins then you will just be killing the chick by cutting through the veins... but at this point sounds like it is zipped locked in and will probably die anyways... If you do help go a tiny bit at a time and with the dull part of a needle in a bathroom that is dripping with humidity from your shower... If you see any blood at all stop wrap it with a wet rag and leave it in the humid warm place for 2 hours and then go back to work on it some more. When you come to the bottom of the shell do not pull it off if it is stuck at all to it;s lower belly or you will open the umbilical and it will bleed to death. Just get down to the belly and then put lots of warm water on the tummy area and then wrap it with the wet rag again and leave it for several hours... I have had one before that had dry membrane stuck to it's feathers after I helped it out... In that case you can always give it a warm bath later on several hours after it has hatched. If you do that make sure you blowdry it dry on the warm setting... Good Luck.