If you are Dell Customer looking for assistance in resolving Dell Monitor Display issue, find the smart ways to rectify screen display problems:
Possible Power Issue
#1 Make sure your monitor power is turned ON/OFF. If monitor is turned on and no power input is available to monitor yet then check your Power Cable is short circuited or in Good Condition. Replace if short circuited.
#2 Else inspect the Video Cable from CPU to Monitor is connected properly. If connected properly, check the same with an alternative video cable. If monitor is working fine with alternate video cable else examine whether Video Cord Slot in CPU is fixed correctly. If not fix it.
These may help your DELL Monitor recover from Display issues in case of power problems.