The monitor was working fine the day before, but when I tried to turn it on in the morning, the screen was black. There was no video, even though the panel backlight was on. Also, the menus were not visible. I followed the steps described in the forums, but they did not solve the problem:

1. Unplug ALL monitor cables (USB/HDMI/DP) from the monitor while the monitor is plugged into power and the white light is on.
2. Then, unplug the power cable from the monitor.
3. Press all the physical buttons on the monitor while it is unplugged and off and wait 30 seconds.
4. Plug power cable back in.
5. Turn monitor on and then plug your USB cable and one video cable back in.

What else can I try? 

Tests were conducted with different HDMI cables and different computers, but the screen remained black.