Your boiler is currently in a temporary holding state and is waiting for a signal from your heating controls, such as your thermostat or programmer, to tell it to start.

DIY fix possible

Check your external thermostat or boiler programmer to ensure they are set to 'on' or calling for heat.Turn the heating temperature dial on the boiler front panel up to ensure it is set higher than the current room temperature.Check if any smart heating app linked to your system has put the boiler into an 'off' or 'away' mode.