I'll copy and paste how I warm mine up from another post I made on a different thread...

I buy my F/T in bulk, and seperate them into sandwich baggies for my feedings. So I have one Zip Lock bag for each feeding basically. I leave the bag out to thaw, and once thawed I then fill my sink with extremely hot tap water (not boiled water just from the tap). Then I put the Zip Lock in the water. The Zip Lock keeps them dry. While feeding I keep this water very hot. When I present the F/T it is extremely warm temperature wise, and the feeding response is incredible. I hope this helps the temperature was the key for my picky eaters especially the spider who was only eating live.

All but one I feed in a seperate container, and I actually have two tubs going to speed up the process. I clean the tubs every so often, but they seem to keep the rodent scent anyway (my wife hates the smell). Now when we put them in the tub they get super aggressive lol. They know it's dinner time.

Hope this helps.