just peel of the outside of the shell leaving the membrane. Its probably mostly white now so the shell should separate easy.
Once you have the white membrane exposed on at least half the egg then wet you hand in warm water (100 F) then wipe the membrane away from the wing that's covering the beak area (do not get water in the beak). The wiping action will make the membrane turn transparent and it should slide away exposing the wing area. Once you have that free gently lift and the head will uncurl. If you see any blood at this point stop and let the chick rest (after 26hours there should be none). The rest is a bit iffy because it depends on what you see and how much the chick wants out. Either way dodge the tummy area picking the shell away from its back area and it should be able to do the rest.
If you are use to doing this its a 20-30 second job once you are set up. I don't have finger nails so I use a nail tool, A lamp if the house is cool, have the water ready and a pinch of flour just in case.
I have no problem assisting a hatch if its not going right. Piping the wrong end or where the chick is making the pip hole bigger with out trying to zip can result in the need to assist (given a little time first). I have never had a chick lost due to a assist but I have had a chick that mother nature didn't want to survive that I assisted then had to deal with (some don't zip because they are deformed, Its a low percentage but something you need to remember)