When the power blips, or you turn the switch off, the program comes back on to the last program you manually input. I don't use the stored programs, and instead set up each smoke in my kitchen, power-off, then hook up to the smoker. When you power on, the program starts from the beginning. So, if the power goes off and on while you're on, say, step 2, the program will start over, but will quickly step to 2 when it sees the trigger is reached (if it's temp).
Set the program before the cook, and no worries. Doesn't matter what program, just set the one unique to that particular smoke.