Baby mice need some form of warmth for the first 3 weeks, usually plenty of bedding and kept out of cool drafts. Both mama and daddy will take turns hovering over babies, and with a fair litter, sibling help keep them warm. They should be kept at 80 degrees and if you are hand nursing babies, they need a nursery tank, perhaps with a heat pad set to low.
Not very common for a mama to reject her young, but if that is the obvious scene, you may have to step in and hand raise the babies. Not an easy task, and means a lot of round the clock work as well as preparation. With more than about 3 or 4 kits in a litter, it becomes next to impossible to save them all without serious help.
You might watch this series of 10 videos to give you an idea what hand raising baby mice is like:
https://www.youtube.com/watch?v=sNX2byHbppM&list=PLIxj-hHVU0wJJq40wp6TOs2tEO05H98pp
I hope the best for you and your mice.
參考: Been there.