I've taken in two crippled chicks from the vet's daughter's kindergarten class. He tried, and no success. I took care of them, had them in a dog pen and would bathe them everyday. One lived quite awhile until a coyote climbed the pen and got it, me and my dog chased her across the farmer's fields, through the wet lands right to her den of pups. Then she was looking to eat me, too.
I learned with a chick that hatched with wry neck, sometimes the hen doesn't eat everything she is supposed to the day she is forming the egg. And how important it is for the chick you are trying to hatch out. I've added 20% sunflower seeds as part of my hens regular diet. Good source of selenium and vitamin E.
So sorry you had to go through this, but my chick was able to sit up and eat. Those two didn't look like they could. I've had a couple with splayed leg, not that severe - used this website, got the bandaid setup and it worked in two days.