Dell P2415q - color cycles

I took a gamble and bought a supposed "new" Dell 24" 4k monitor from a local auction for $50. It's a model P2415q. Of course, it's an auction with no returns. You win some, you lose some.

When I turn the monitor on, it powers up but is stuck in a color cycle mode showing a full white screen , black, red, green and blue and keeps repeating. It does this if it is plugged into my computer (using HDMI) or with no other cables plugged in. Eventually, it goes into a power save mode and the power button glows off/on.

My video card I have hooked up to it is an Nvidia 970. It has HDMI and DVI - the monitor accepts HDMI and DisplayPort. I just have power, usb, and hdmi plugged in right now.

I found a page on Dell's forums that said you could power off, hold down the top two buttons, power on then hit the top button to get to a diagnostic screen and turn off this mode. I can't get this to work.
None of the on screen controls work. If the monitor is asleep, it just wakes up the the color cycle problem.

Any one have any ideas? I'm thinking I lost $50 at this point. I got some other good deals (non-computer related), so all in all, not going to cry and moan too much about it.

The monitor looks new - but there is probably a reason the auction ended up with it.

Panel is probably in self test mode. Likely there is either a loose cable or the main control board is bad.

I found out a bit more about this monitor. It is stuck in "burn-in" mode. If your monitor works, this particular model you are supposed to go to factory settings to turn off burn-in mode. Power off, hold top two buttons in, press power on - let go of all buttons. Press top button again. Except, mine doesn't do anything. A Dell support employee actually emailed me on their support forum and gave me a few things to try - alas, I'm screwed I think.
Unless anyway has any ideas, I think I'm chucking this one in the trash next week.