Boiler will not start at all, no display or lights

Safety: Only work on electrical components if you are competent and local regulations allow.

• Check power source: Verify the fused spur is switched on and the fuse is intact. Replace with the correct rating if blown.
• Consumer unit: Check that the circuit breaker feeding the boiler has not tripped.
• On/off switch: Operate the boiler's main switch several times; if loose or intermittent, it may need replacement.
• Internal fuses (technician): A professional can check and replace PCB fuses and test for underlying faults that caused them to blow.