It may be too late to return it to the store, but there usually is a warranty period of some kind. I would try to exchange it, or failing that get it repaired under warranty. It sounds like the LCD screen had a defect and probably the whole LCD pannel will have to be replaced. Failing all that and you are just stuck with it, I think the price of repair might exceed the value of your set. Making the best out of a bad situation, I would get a DVD player and pause it on a dark image so as to highlight the light leakage. I then would get a small pointed Sharpie marker and darken the light spot. I would prefer a black dot to a light leakage, but that is just my preference.
