its good to completely thaw the rodent at room temp and warm it either under a heat lamp or placed in a zipp lock bag and placed in hot water for a few minutes making sure the rodent doesnt get wet and lose any scent. be especialy careful the rodent doesnt begin to cook because snakes connot digest cooked food items. if the problem continues you could try getting some hamster or gerble liiter from a local pet store and put the frozen rodent in it to get the diff scent on the rat. Bps love gerbles and hamsters but tend to get picky and want the gerble or hamster scented food after that. you also could try exposing the brain a little. it sounds gross but it works.