Water heater does not start at all; no lights or display, completely dead.

Safety: Before any work, ensure the appliance is isolated from the mains at the consumer unit.

• Check household supply: Verify that the circuit breaker or fuse feeding the Immergas water heater has not tripped or blown. Reset/replace only once; if it trips again, there is a fault.
• Inspect power cord and plug (if fitted): Ensure the plug is fully inserted and the cord is not damaged.
• Check appliance switch: Some models have an on/off rocker switch on the front. Confirm it is in the ON position.
• Internal fuse: If accessible in the terminal block area, check the appliance fuse and replace with the same rating if blown. If it blows again, stop and call a technician.

Warning: Do not open the sealed control board or work on live circuits unless you are qualified. Persistent power issues require professional diagnosis.