Repairing a monitor? Any Ideas on what's wrong with it?

I recently bought the Dell SE2717HX monitor on sale for $100, brought the thing home and it was broken. It would display my pc fine for a minute or two but would always end up flashing solid colors for a few seconds each as if it was stuck in a test mode. I contacted Dell and they sent a new monitor out and said I could dispose of the broken one myself. I was weary about opening the broken one up and ruining my chance at a replacement but now I have nothing to lose.

The problem seems to be with the inputs on the monitor as when the monitor has nothing to plug into it the thing functions fine. Any ideas as to what part failed on the monitor and if it can be fixed?

The fact that it happens after a minute or two seems weird to me however I have heard of this in the past and on Dell monitors for that matter. If I recall correctly there is a self test mode or "screen burn in" type setting on some of these monitors and they are usually enabled and disabled using a button combo.

This sounds all the world like diagnostics test as they do flash colours just like what is described here.

First thing I would try doing is to factory reset the monitor through the OSD and see if that will do the trick. There are also some tips on the Dell site about how to enable the diagnostics test, which I imagine will work in reverse order too for disabling it.

http://www.dell.com/support/article/uk/en/ukbsdt1/SLN302678

Assuming that is the case I'm quite surprised Dell didn't explain that was the issue, but can't be bad to a free monitor anyway right.

Yea I googled around a bit before chatting with the dell rep. The flashing looks just like the burn-in mode that others have seen. The only problem is that I can't access the menu at all once the colors start flashing, which is not supposed to happen. For the couple minutes that I could access the OSD (you can only access it when you have a working input that's displaying something) I tried to do a factory reset but it didn't help. Tomorrow I'll try out that diagnostics test in reverse order.

Maybe @wendell might have an idea of what it could be.