Assisted hatch chick no fluffing up

[RoiKuro]

My Cochin was sitting on 12 ayam cemani eggs and 3 hatched. Two days later, she got of the nest and went from broody mode to mother mode. One of the remaining eggs was pipped but the mother hen wouldn't sit on it. I put it in my greenhouse and over the course of 6 hours, I helped it hatch. It got out and my dad came home and made a brooder and put it inside. It had a small bit of yolk( I think) on the back but I just left it there. It has been 1 and a half days in the brooder and not fluffing up. What should I do before I put it with the hen?

 

[Lollychicken]

If it's eating and drinking it should be fine, just make sure it stays warm and it should start fluffing up