Dell P2419HC User Manual page 50

When the monitor enters the Power Save mode, the following message appears:
Activate the computer and wake up the monitor to gain access to the OSD.
If you press any button other than the power button, the following messages will appear
depending on the selected input:
If either HDMI, DP, USB Type-C input is selected and the corresponding cable is not
connected, a floating dialog box as shown below appears.
or
50 | Operating the Monitor