Your boiler is currently set to a manual testing mode used by engineers to check emissions, and it won't operate normally until this is switched off.

DIY fix possible

Locate the small button or switch with a 'chimney sweep' or 'bin' icon on the control panel.Press and hold the button for a few seconds until the light stops flashing or the display returns to normal.Turn the boiler off and back on at the fused spur switch to reset the operating mode.