Were I in your shoes, I would take the rat out of the freezer and allow it to thaw all day long in the snake room (by the tub or cage or viv, etc.) I would want it to be very very thawed! I mean REALLY thawed!! I would turn off the lights to where the snake is kept and wait an hour. After that hour of darkness has passed, I would get the rat and blast it with a blow dryer (in another room) to bring up the heat signature on the head. I would then go to the snake and zombie dance the rat. BAM!!! Good snakey.....