Your boiler has detected that the temperature is too low and has paused itself to prevent the pipework from freezing.

DIY fix possible

Ensure the room thermostat and radiator valves are turned up to allow water to circulate.Verify that the boiler's electrical supply is left on to allow the built-in frost protection to run.Gently warm the area around the boiler or pipes if they are located in a very cold garage or loft.