Diagnosis
The Mysa thermostat is not receiving the 120V or 240V power required to energize its internal circuitry. Since the heater functions when wired directly, the electrical supply to the wall box is active, but the power is not reaching the device's logic board. This is typically caused by a tripped breaker, a loose neutral wire connection (which prevents the circuit from completing), or a catastrophic hardware failure of the thermostat itself.
How to Fix It
Follow these steps to restore power to the display:
- Verify the Breaker: Locate the circuit breaker panel. Even if it looks "on," flip the breaker for the heating circuit completely OFF and then back to ON to ensure it hasn't partially tripped.
- Check the Neutral Connection: Power down the breaker. Remove the Mysa from its wall plate. Ensure the white neutral wire is securely fastened to the corresponding terminal. Unlike traditional thermostats, Mysa requires a dedicated neutral wire to power its screen and Wi-Fi chip; if this wire is loose or disconnected, the screen will remain blank.
- Inspect Line Voltage: Ensure the "Line" (incoming power) and "Load" (outgoing to heater) wires are firmly seated in their terminals and not touching each other, which would cause an immediate short.
If That Didn't Work
If the wiring is secure and the breaker is on, try the following:
- Hard Reset: Turn the breaker off for 60 seconds and then back on to attempt a power-cycle of the internal processor.
- Voltage Test: Use a multimeter to verify that there is actual voltage present at the Line and Neutral wires while the device is disconnected.
- Hardware Failure: If you have confirmed 120V/240V is reaching the terminals but the screen remains dead, the internal fuse of the Mysa has likely blown, and the unit must be replaced.
Heads Up
Always turn off the power at the breaker panel before touching any wires. Electric baseboard heating uses high voltage that can cause severe injury or death if handled while live.