there is never any need to crack open the skulls. if your humidity is right, and you are patient and don't push and stress the snake...it will eat. all of the silly experimental feeding techniques are not needed. leave the animal alone for a while, wait till evening when there is barely enough light for you to see without turning on the lights, and with tongs...dance the mouse around...when the snake notices it, slowly move it closer. a lot of you are suggesting stuff that is just not needed. they will eat. make sure your environment is correct, don't stress them, and they will eat. too many of you are making something so simple, WAY too complex. twenty plus years of dealing with so many different species has taught me well, let the snake...be the snake. match its natural habitat as much as possible, don't stress it....and it will eat. real easy.