Article reference KA-01675
The DAR radiator has a main power ON/OFF switch behind the radiator. If you feel behind the right hand side of the radiator as you look at it on the wall, you should feel where the switch is located.
View from behind radiator:

Make sure that it is switched on, make sure the switch on the wall is on and check your consumer unit for any tripped breakers or blown fuses. If the product is still dead after making these checks, please raise a support ticket.
Applicable models:
DAR050 DAR075 DAR100 DAR150 DAR200