U2412m DVI connection not showing Images can only access input selection menu

To start, Dell does not test/validate this monitor on Apple proprietary hardware, ports, and software.

Open the U2412M User's Guide page 42. Run both the Self-Test and Built-in Diagnostics. If these pass, the monitor is functioning. The culprit is either the DVI to HDMI cable or the computer. I would then move the monitor to a Windows based computer and test using the Dell provided cabling =
Computer VGA out --> VGA to VGA cable --> U2412M VGA in
Computer DVI out --> DVI to DVI cable --> U2412M DVI in

If the test fail, get it exchanged.

The monitor passed both the self test and built-in diadnostics. I verified it's not the computer nor the cable by checking with alternate cables, and monitors. I also tried using another computer (macbook air) and got the same results on the u2412m.

My rMBP is also running windows 10 (64 bit) via bootcamp, Even when running windows the u2412 exhibits the same issues. I've also tested going DVI --> DVI via a functioning thunderbolt adapter which did not work. I currently don't have a computer that runs VGA to test out that but can get access to one eventually, but if I can't get the DVI working, it doesn't do much good for me.

Then get it exchanged. Test the replacement before sending any monitor back to Dell. If the replacement does not have the issue, keep it and send us the original. If the replacement has the SAME issue, the monitors were not at fault. Send the replacement back to Dell.

Chris,

So I called support and they tell me they can't locate the serial number in their database. They keep bouncing me from department to department. Anything you can do to help me out? here is the screens monitor's serial number:

CN0YMYH17426141965GL

FYI - when using a VGA connection (borrowed a friends old laptop) the screen works fine, but still no luck when using a dvi connection.

They cannot "see" a Dell monitor PPID serial number in their tools. They can only see a Dell specific number (order, customer) which you only get when buying directly from Dell. Did you buy the monitor directly from Dell?

Chris:

I don't know if the monitor was bought directly from dell. The monitor was gift, and the person who gave it to me doesn't know/doesn't have a record. I suspect it was purchased from another retailer online. That being said what I do know:

• The DVI connection does not work
• The VGA is fully functional (I'm waiting for a cable to test the display port should be here by end of the week)
• according to the back of the panel the model # u2412mb (Did not notice the "b" until just now
• according to the back of the panel the screen was manufactured in January 2014 (I attached a photo of the back)
• Until a few weeks ago, I've been extremely happy with it, particularly the stand, and the extra lines of resolution
• This screen is supposed to come with a 3 year warranty.
• Going off a manufacture date of January 1st 2014, the screen should be covered under warranty until December 31st 2017 at minimum regardless of when the screen was originally purchased

Given all this information am I out of luck in trying to get this exchanged? 

Based on the serial number CN0-YMYH1-74261-419-65GL, the manufacturer date was January 9, 2014. So the warranty would be to January 9, 2017.
* Open this
* Read, "Monitors without a service tag number purchased from resellers (Amazon, Best Buy, Buy.com, Cost Co, Walmart, Sams, other online store, etc.)"