Was this purchased directly from Dell as new? What is the 20 digit S/N and A0x revision? When all of the cables were disconnected, did you press and hold in the power button for 10 seconds, then reconnect and retest?
I purchased the monitor through an re-seller ans as a new (sealed box,etc')
S/N :CN-0VGGY4-QDC00-79Q-0LMU-A02 (Israel)
Yes, but I re-re-re-re-re-retested again and suddenly it started working, I now wonder if it would happen again.
Built on September 26, 2017. So they had it for 6 months. Unknown as to if it will happen again. You need to transfer the service tag number into your ownership.