Why is my 4iE Screen blank ?
4iE Smart WiFi Thermostat
If the 4iE screen is blank check the following:
Check that the standby /display brightness is not on the lowest setting “0”. If you have set the standby brightness to 0 you will need to press the standby button at the bottom of the main screen to activate the screen so that you can see the display. If you do not want the screen to go blank when in standby mode change the display settings.
If this is not what is causing the issue, an electrician will be required to check that the thermostat has been wired up as per the wiring diagram and that the thermostat is receiving 230V.