If he's not acting like he's in shock, then you provide a heat source, clean water and wait hopefully for him to recover. (He won't need food until 72 hrs of age, and he won't want it until about 30 hrs of age.)
If he is acting like he's in shock (sleepy, cold, no noise) then he needs warmed up ASAP and maybe some electrolytes in his water. (2 qt water, 1 tsp baking soda, 1 tbsp honey/sugar/corn syrup, 1 pinch salt.)
In both cases, if you have poultry vitamins, I'd use them.
I'd also keep a very close eye on any hatching eggs, in case she does this again.
You'll have to separate the chick(s) from the mom and put them in a brooder and raise them accordingly.
As far as the wounded chick; mix 50/50 betadine/water and apply to wounds, gently pat dry and apply neosporin as needed until healed.
The neosporin will smother mites and kill them. Gently apply permethrin dust to the rest of the chicks body as best as you can. Do this away from food and water sources as not to contaminate it.
Reapply the dust in 10 days.
Also give the chick Poultry Nutri drench orally to the side of the beak using an eyedropper. Use a small eyedropper and not the one provided in the bottle, it's too big. Give the chick one drop twice a day for no more than 5 days.