Why does the red reset button keep coming on when my boiler is turned on ?

my alpha 280e boiler fails to fire up when switched on.. the boiler has gas, water and electric supply.
the thermostat and programmer all appear to be in working order. each time i either turn on for hot water on heating, I can hear the boiler fan turning but fails to ignite then the reset button lights.
I have cleaned the electroes but still does not work...........Help please.