The thermostat display is very dim or the backlight flickers.

Safety first: Isolate power before touching wiring.

• Check brightness settings: In the thermostat menu, ensure the backlight brightness is not set to minimum or eco mode.
• Inspect wiring: Tighten any loose power terminal screws and ensure conductors are fully inserted.
• Measure supply voltage: If competent, use a multimeter to confirm that the supply voltage is within the specified range under load.
• Test after power cycle: Turn power off for 30 seconds and back on. If flicker persists with correct voltage, the backlight circuitry is likely failing.
• Replace thermostat: Display hardware faults are not repairable in the field.