Condensation or visible moisture inside the thermostat housing or on the display.

Safety: Moisture can damage electronics. Avoid using the device until it is dry.

Steps to mitigate:

• Dry the area: Gently wipe external moisture and allow the thermostat to dry naturally in a warm, dry room. Do not use hairdryers or heaters directly on it.
• Relocate thermostat: Move it to an internal wall away from sources of damp or condensation.
• Investigate damp: Check for water leaks or structural damp in the wall and repair as needed.

If the thermostat malfunctions after drying, internal corrosion may have occurred and the unit should be replaced.