Perhaps you have not inserted the plug properly into the wall socket.
Perhaps there is a power failure. Check if the power supply works by connecting another appliance.
Perhaps the power cord is damaged. If the power cord is damaged, you must have it replaced by Philips, a service centre authorized by Philips or similarly qualified persons in order to avoid a hazard.
Perhaps the display setting is too low. Turn on the lamp to a high setting, this will increase the display brightness or make the environment less bright. Increase the display brightness in the (SET) menu.
Perhaps direct bright sunlight shining on the appliance is blinding the display. Remove the direct sunlight from the appliance.