Is it the real room temperature that can be seen on the display?
If not,the thermostate needs calibration. Calibrate the device according t the description in the instructions manual.
When the thermostat is turned on press the button so that the set value exceeds the room temperature. Is the heating icon appearing on the display in a few seconds with a soft clicking sound?
Does the thermostat control a surface heating system?
YES -Check the controller’s surface limit values as described in the instructions manual.
If necessa, the setting limit value can be increased. If the surface temperature shows an unrealistic value, further examination is required. If there is a piece of furniture, a carpet or other heat insulating material over the floor sensor of the thermostat, remove it so that the affected surface can give off heat. If there is no such a reason, the sensor might be damaged.
NO -the thermostat need to be further examined, So please, contact after sales send back to the original factory for repair or replacement.