Warning: The installation of high voltage equipment should be performed by a qualified electrician. Please ensure that you comply with local electrical codes and regulations. Improper installation can lead to device failure and even cause a fire. Damage to thermostat due to improper installation is not covered under warranty.
Is your heater still running even after successfully installing your new Mysa thermostat and connecting to WiFi and the Mysa app?
If this is the case there is a good chance that there may have been an issue when wiring the Mysa unit to your gangbox. In most cases this results from misconnecting the load wires, in this scenario the heater bypasses the thermostat altogether resulting in a state of constant heat.
Luckily, this is more often then not a simple solution!
To correct this follow the diagram below - be sure to turn the unit off before proceeding!
As you can see from the image below the cause of the problem is coming from the fact that a load and supply wire is going to the Mysa L2 wire.
To correct this you would transfer the extra load wire to the Mysa load wire which should now have two wires running to it.
Turn the unit back on, ensure the thermostat is set below the current room temperature, the heater should no longer be constantly on.