What is Causing my My Samsung la40d503 to flicker green

how extended is that warranty, and what does it cover? Sounds to me like a classic video controller board about to fail.

Listed as a laptop--if a TV is a Samsung or what?

According to your observation in the black flickering lines this fault is from your t-con board there may be a loosed solder or cold solder from the t-con or to the logic board. This kind of trouble is fixable but it should be done in actual testing of the unit to be sure where the fault is. I suggest that you should contact a technician to do it for you and save you from stress. Good day and best regards.

The front panel LED light indication "LAMP" flashes?Change the the tv projection lamp or LED lamp first,see what happen?Than go from there?Tvs with "LAMP" LED indication light flashes,tv 1 1/2 or 2 years old use like 4 or 5 hours a day.The projection or LED lamp or bulb,inside life span is over.Require changing LED lamp or projection bulb.

If you get green vertical bars or green dots in the picture but not in the menu screen (Digital board symptom)

The x-sus or y-sus panel wil be the fault.Check the fuses on these panels ,if one of the fuses is open then that panel must be replaced.Not verry cheap to replace.

Check and replace damaged component/s at its horizontal scan output section circuit. Check the LOT (Line Output Transformer) too for damage. Replace the horizontal scan output transistor. Check the input voltage to LOT. If the voltage is absent check the feeder resistor; if any. If you wish to get some details; check the site linked here. Pull up older posts.
http://electronicshelponline.blogspot.com/ Type in this key phrase " my service table today " in the search box at the top right of the the home page, to get gathered some pages which has the details of practical experiences of the author of that site. The search result might display about 20 Nos of related posts. Press the "All posts" at the bottom of the list, then you can select them one by one.

Just unplug and plug back in. Worked for me.

Try it a few times.

May not work for everyone.

soon the picture going to go to black screen, you got somes capacitors bothering, you better to call a tech now that he can see the problem, later will cost you more..good luck ps the picture many times tell to the tech whats going on.