Well mine has now stopped working, just a blank screen. No diagnostic window when tested. Huh.....!!
My goodness did I need to jump through hoops with Dells support.
Two call transfers asking for the exact same information, you also need the Service Tag from the rear of the monitor.
Then, whilst the agent is on the phone, you need to take a photo of the rear of the monitor with service tag and serial number showing, after running through their diagnostics.
They wanted me to go through various cables and try another computer, huh. Just power on without a connection and it should go through a diagnostic POST and then display the no cable attached window, which it didn't. Eventually they accepted it was faulty and so email sent.
Of course the agent couldn't find the email and needed to provide her own personal address to send it to.
Finally received the email to her personal address, then she had to verify the serial number that it was genuine and in warranty.
All was done ok and now waiting for a replacement to arrive, apparently the courier will deliver the new monitor and then call the following day to pick up the old one. I would have preferred then to collect at the same time as dropping off, but it doesn't work like that.
Roll on a replacement, hopefully it will look, screen wise, as good as my first - but last longer....!