One thing to make things easier while you search for SOME kind of image is to take one video cable from the DVD player's yellow video jack and plug it into the yellow jack on the display; if that doesn't work, take that ONE cable and run it from the Green output to every video input on the display, one at a time, until you get an image. The Green output will give you just a black and white image, but once you have that, you can add the other two cables for color. This makes it easier to do while you are reconnecting things.

Also, if you get a garbled image, get into the menu of the display to see if the display can be changed to show different resolutions, and try them all. Sooner or later you should get a combination of input and resolution capability that will show something, unless, say, your DVD player is outputting PAL and the display just can't show PAL at all.

Then take it back to the dealer and see if they can figure it out.

Yes, I said take it back to the dealer. Oh, you bought it on the internet???......