slide open the battery draws on the stat and let the display go blank. turn the boiler off at the mains. turn the boiler back on at the mains elctricity. push the overide button on the reciever so the green light comes on. push button 2+1 and hold them. the red light will flash quickly then go out. release the buttons. then push in the left battery drawer followed by the right. the red light should start flashing on the reciever. now turn the temperature up and down an see if the boiler goes on/off. if it doesn't work don't give up just try it again
Paul the gas man, February 2008