If this issue occurs, please proceed with the following solution:

1.    Workaround: check the power supply. 
Please ensure the following: 
-    The POS player has power and is turned on (check blue power indicator).
-    The HDMI cable is plugged into both the POS player and the screen.
-    The source on the screen is set correctly (e.g. HDMI 1).
-    The screen isn’t set to a power saving mode (automatic screen turn off after x hours, “Eco mode” or similar).

2.    Workaround: check the cables and device inputs. 
Please conduct the following steps: 
-    Try a different HDMI cable.
-    Try the second HDMI output on the POS player.
-    Try a different HDMI input on the screen (set source on the screen accordingly).
-    Try connecting a different device (e.g. another POS player) to this screen.
-    Try connecting this POS player to a different screen.