Perform some quick tests:
Power supply
Remove the Thermostat's batteries for one minute, then put them back in, checking their polarity: the display should flash.
If it doesn’t flash, try again with new batteries.
If it still doesn’t flash, please contact us.
Buttons
If the display flashed in the last test, wait for the temperature readings to appear.
Now test the buttons (+) and (-): the Setpoint temperature should increase and decrease.
N.B. The buttons are not touch sensitive (you must hear a click).
Updated