I would try to still hatch the baby you opened. That way at least you know you tried.
If you going to try to keep the one you opened alive, you need to moisten the membrane inside the egg so it can poke through it, and keep it moist. Here's a link to a webpage on assisted hatches for cockatiels. Most of the information transfers to chickens as well.
http://justcockatiels.weebly.com/assist-hatches.html
Good luck and keep us posted.
If you going to try to keep the one you opened alive, you need to moisten the membrane inside the egg so it can poke through it, and keep it moist. Here's a link to a webpage on assisted hatches for cockatiels. Most of the information transfers to chickens as well.
http://justcockatiels.weebly.com/assist-hatches.html
Good luck and keep us posted.