I managed to keep a little baby alive for a few days before he unfortunately passed away. This does not mean your baby will pass.
I held the baby as much as possible, and when I went to sleep, I had the little creature nestled into elbow. I know its sounds radical but Pipp is right, the baby MUST have warmth, one way or another. There were no siblings so I had a hot water bottle covered in a pillow case and made sure it was the right temperature, not too hot, the baby nestled up against it. I set my alarm and changed the bottle frequently.
I am hoping for the best here.
Please let us know how it goes
I also had the baby feed from the doe a little more frequently than normal, I think it was 3 times a day, check to see if baby has a round tummy and baby should want to sleep immediately after a feed. Do not move or otherwise stimulate baby, the idea is warmth, food, growth and sleep. However if you notice baby is NOT producing any poop, you will need to gently ( very gently massage babies tum), monitor poop and urination.
Place baby with the others for warmth too, as I just remembered that my baby bun was a single so the hot water bottle came in handy, it kind of doubled as a nest full of siblings.
Anyway its just what worked for us.
Good luck