I had the same problem with mine after a power cut and it affected the PCB board.. it needed to be replaced. Luckily i have british gas cover, but really they should not have replaced the board because there had been a power cut. Im having problems again with mine. I have come home from work past couple of nights and no heating or hot water, light stays on reset, after messing about resetting and switchin on and off, i have enventaully got it working. British Gas due to call out 2mora, another day off work.
doddler
December 2008