Boiler not working!?

Hi all,

Could anyone advise on some basic fault detection methods for boilers? I have a Vokera Compact HE with the following issue...

It started when I bled a radiator. The pressure in the system went down and therefore I 'topped up' the system by releasing the water inlet valve. The system pressure is now at 1.5 bar.

The boiler now doesn't start. There is a flashing red light which indicates a fault. There is a sound for about 10 seconds when I try to start the system (not sure if this is a fan or a pump?) but does not continue on to fire up.

Any help on this would be greatly appreciated!

Many thanks,

Ian