Sorry about the losses. The only thing I can think of is that your temperatures were too low and that's why they are developing so slowly. At this point, who knows if the chicks will absorb their yolk sacks or not, or if the ones you have left will hatch normally. All you can do is wait it out or pull the plug and try again.
Maybe someone with more experience will chime in and give you better info.

Maybe someone with more experience will chime in and give you better info.