You need to take immediate action if there's any hope of reviving it. Sometimes super cold babies can appear dead. I had a litter of four, born on the wire... That I got to just in time. Got them warm via a heating pad and my body heat...
Needless to say, they died anyways. But I think they were more peanuty than viable baby. (They did live for another three days. Never grew dispite being fed.)
The other one I brought back ended up having seizures, bloating, and dying.
So I've heard of it working, but I've never experienced it myself. I figure if the doe is going to raise the litter, she's going to get the babies all in the box like she should. If you lose one, then you lose one.