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

Safety: Do not remove the boiler cover unless you are competent. Electrical work must comply with local regulations.

User‑level checks:

• Check that the fused spur or plug supplying the boiler is switched on.
• Inspect the fuse in the spur (typically 3A) and replace with the same rating if blown.
• Check your consumer unit for a tripped breaker and reset if appropriate.
• Ensure any external controls (room thermostat, programmer) are calling for heat and have power.

If the boiler still shows no sign of life, an internal fuse or the PCB may have failed and should be checked by a heating engineer.