Thermostat display completely blank, no lights or response

Safety first: Before removing covers, switch off the heating circuit at the consumer unit and fused spur.

Steps:

• 1. Check fused spur: Ensure the boiler/controls fused spur is switched on. If it has a replaceable fuse, isolate power and replace with the correct rating (typically 3 A) if blown.
• 2. Check consumer unit: Look for any tripped MCB or RCD on the heating circuit. Reset if safe to do so and investigate why it tripped if it happens again.
• 3. Inspect thermostat backplate: Remove the thermostat and verify that live and neutral are present and firmly connected. Use a multimeter or voltage tester if competent.
• 4. Battery models: Replace all batteries with new, high‑quality alkaline cells, ensuring correct polarity. Clean any corrosion from the battery contacts.
• 5. Test after restoring power: Refit the thermostat and check if the display comes on. If still dead with confirmed power, the thermostat is likely faulty.