Boiler will not start at all, no display or lights, completely dead.

Safety first: Only work on electrical components if you are competent. Always isolate at the main switch before removing covers.

Step-by-step checks:

• 1. Check external power: Verify that other electrical appliances on the same circuit work. Check the consumer unit for tripped breakers.
• 2. Inspect fused spur: If the boiler is connected via a fused spur, switch off, remove the fuse, and check/replace it with the correct rating (often 3A).
• 3. Check boiler switch: Ensure the boiler’s main power switch is in the ON position.
• 4. Internal fuse (for skilled users): With power isolated, remove the boiler front panel and locate any internal fuses on the PCB. Replace only with identical types and ratings.

When to stop: If fuses blow repeatedly or there is evidence of burning, do not re-energise. Contact a qualified electrician or heating engineer.