High humidity during the incubation period can cause 'hatching deformities, like crooked toes. Wry neck is caused by a vitamin/mineral deficiency. And as @Nabiki , said, usually doesn't cause death, unless so severe as not to allow them to eat and drink.
You have other issues, possibly in the brooder setup? Can you post photos of your setup?
might help to determine what exactly is going on!
You have other issues, possibly in the brooder setup? Can you post photos of your setup?
might help to determine what exactly is going on!