What do the two flashing circles in the display mean?

This means the boiler is running in its air-purge mode. The air purge gets rid of air from the boiler’s heat exchanger to stop it overheating.

This can take up to eight minutes to clear after switching the mains power on to the boiler. During this time the pump will switch on/off intermittently and there will be no central heating or domestic hot water delivery.