Look for a smooth metal "stud" sticking out of the inside back wall of the smoker. That is the temperature probe. I don't know if they have updated the software since they made mine, but when the probe was registering 32 degrees or less, the control unit would error out with a divide by zero error. The easiest solution is to take a hot and wet washcloth, and hang it from the end of the probe. Then you turn the unit on and it will heat up. Just take the washcloth out after the unit hits 100 degrees or so.
People were doing stupid things to try and fix this, like removing the control unit and bringing it inside, or bringing the whole cabinet inside to warm it up. They all assumed that the cold weather was bad for the electronics, but that is just not the case.