Your boiler has temporarily paused itself because it detected that the water temperature is rising too quickly, suggesting there isn't enough water circulating through the system.

DIY fix possible

Check the pressure gauge on the boiler front or digital display and ensure it is between 1.0 and 1.5 bar.If pressure is low, use the filling loop underneath the boiler to top it up.Ensure all radiator valves and the boiler isolation valves are fully open.Bleed your radiators to remove any trapped air pockets.