What you do after you trun it off is reboot the computer. What is isn;lt doing is seeing the flame it has a hot plate ignition I suppose.
ON the left side of thr main birner is somthing that looks like a wire in a porcilain socket that is just above a burner row. that's the flame sensor clean it if that sin;t working the furnace won't run. a Season of sitting will allow engih carosion to keep it from seeing the flame what it privides to the computer is a small current that is sent across the flame.
I have enclosed a link to payne sevice lituratire for you:http://www.paynehvac.com/techlitcd/html/PROC.html