Your boiler is currently running an automated air-removal cycle to clear trapped air from the system, which is a normal process after maintenance or a power restart.

DIY fix possible

Wait for the cycle to complete, which typically takes between 10 to 20 minutes.Ensure your heating and hot water are still turned off at your thermostat while the process finishes.If the boiler does not resume normal operation after 30 minutes, switch the power off and back on at the fused spur.