this is the advice someone gave me
Take the mouse and put it in a ziplock bag, seal the bag and slam the bag 4 times AS HARD AS YOU CAN (not slamming hard will make the mouse suffer). Take the dead mouse out of the bag (it still might be twitching) and give it to your BP. I suggest using hemostats/tongs/forceps and give it a little motion and your BP should take it. kill hoppers the same way as adults, to kill fuzzies give them 5 very very hard flicks on the head and they will die. Just put these in front of the BP, move them closer to the head of the BP for best effect. Don’t tap the BP on the head with the mice though. After they eat FK twice try feeding frozen. Completely thaw out the mice (on a plastic bag that is on a piece of metal), then put them in zip loc bags and put the bag in a jar of VERY Hot (as hot as your sink goes) water. seal the jar and run the very hot water over the jar. after around 15 minutes (if your mice are room temp) they will be hot enough to feed.
hope that can help