Helping before a pip usually kills a chick. It is not easy to crack the shell and leave that membrane intact. Sometimes, chicks just don't hatch. It's just the way it is. It doesn't mean that the shells are too hard. It could have been a lot of things. Maybe the broody didn't turn them...
Like I said earlier, they can stay in there for about 48 hours before pipping. This is probably the hardest stage of hatching. You hear them in there, but you have to leave things alone. No touching or helping. If you try to help, you can end up killing the chick. Most of the time, hard shells...
Deep breath. The peeping means that the chick has broken into the air cell and is getting into position for the external pip. This stage of hatching can take anywhere from 12 hours to over 48 hours. Just keep that humidity up, and be patient.