Screen On My New LN40A630 Goes Blank After A Few Seconds.

Samsung.com FAQs says:

"If the screen on your LCD TV goes off a few seconds after you turn the it on, blanks out, is dimming, or doesn't go on at all, it's likely that the TV's backlight is failing and you need to get the TV serviced."

How can this be possible? I just bought it yesterday. Supposedly a brand new TV.

What happened:
1. Took it out of box, hooked it up to HD cable box via component cables, and turned everything on. Screen snowy, but began prompting me thru the initial set up, then after 10-20 seconds, the screen went totally green, then after another 10-20 seconds, went totally black. I can't access the menu at all.
2. Finally, after checking everything a million times, I figure maybe it's the cable box or I hooked it up wrong.
So I hook it straight up to the cable, no box. And it works. I'm able to get all the channels, except HD of course since no box. I fiddle with settings a bit, and watch it for 30-45 minutes. Now I was really convinced that it was the box.
3. So I try box again. Get audio now, but no picture at all. Fiddle with it for hours it seems trying to get it to work. Can't access menus or anything.
4. Finally, I just hook it up straight to cable again (no box) to see if that still works. Get picture and channels for 10-20 seconds before it goes green, then totally black like before. Can't access menus at all.
5. Now I unplug cable completely. I just want to power the TV and try to access menus. I turn it on. Static of course, and I can access menus. But only for 10-20 seconds, then green screen, then black.
6. Repeat steps 4 and 5 over and over.

So could it be a failed backlight or something to that effect? This has been the worst purchasing experiences of my life. I just hope the store will take it back. I'm not sure if I want to try to get another one of these models or what.