If you are going to brumate, you need to get the temps down to a stable 54.F/55.F and no lower or higher. Unplugging the heat pad is likely not going to do this effectively. Keep in mind that if temps are cool, but not low enough for the snake to go into its hibernation state, you are risking giving him conditions that can lead to severe RI or like infections; if the temps get too close to freezing it can cause irreparable nervous system damage or death.
Sounds risky, but its really simple. Get a wine cooler with a thermostat and set it for 54.F and use a thermometer to cross reference the actual temps.