Circulation pump is running, flame is off (green “Flame On” LED not lit), boiler blower is on. The thermostat may or may not indicate it has the boiler turned on and once the boiler goes into fault condition, it doesn’t pay attention to the thermostat telling it to shut off. If you put your ear on a radiator, you can clearly tell if the pump is running and if it’s at an unexpected time or the radiator isn’t hot, then you should go check it.
The indicator panel will be flashing “F09” and the fault LED will be lit up. (see pic below)
Repair
Turn off boiler using switch on red “Emergency Switch” faceplate (see pic below)
turn on trouble light if needed (it’s setup next to the boiler)
remove gray cover
remove 2 screws for flame detector (bottom right - see pic below)
lightly abrade with scotch brite which is under boiler