All LCD TVs have a light source behind the screen. Sometimes the light comes from LEDs, but more often it's a fluorescent light. If the TV fell or was dropped, it's possible that the light was damaged. That sort of damage is generally not covered by the manufacturer's warranty. And depending on the original cost of the TV, repair may simply not be worth the cost. You would have to contact the TV manufacturer (Onn) and inquire about warranty repair and where they might offer repair services.
Dan
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