Thermostat display is completely blank and unresponsive.

Safety first: If your thermostat is mains or 24V powered, isolate power before removing it from the wall plate.

• Check batteries: For battery models, replace with new alkaline cells and ensure correct polarity.
• Reseat thermostat: Remove the thermostat from its wall plate and refit firmly to ensure good contact with the backplate pins.
• Check hub power (for wired models): Confirm the Heat Hub or 24V transformer is powered and its fuse is intact.
• Test another location: If possible, try the thermostat on another known-good backplate.
• If still dead, the thermostat’s internal electronics are likely faulty and the unit should be replaced.