How can I re-establish power supply to glowworm compact 100e combi boiler?

I've had a couple of problems in the past year with this one. A leak coming from underneath the boiler and a burnt out part on the circuit board. Both have been fixed but the plumber did say that it still doesn't sound that it's running that well. Anyway yesterday it broke down. We don't have any power supply. My husband has tried changing a couple of fuses with no success. Has anyone got any other ideas? Many thanks, Vicky