Hi. It looks like the backlight on your LED TV has failed. LED TVs feature long thin circuit boards with surface-mount LEDs packaged every few inches. Direct backlit TVs have quite a few strips with the LEDS spaced out over the area of the LCD panel. Edge lit LED Tvs have the majority of the LEDs on the sides of the LCD panel. It looks like your TV is direct LED backlight.
While LEDs can be more efficient and durable than other forms of lighting, it is up to the manufacturer to produce and implement a well designed power system where LEDs are driven within their specification, and create an environment where the LEDs can properly dissipate heat. Unfortunately, it seems that many TV manufacturers are intentionally creating poorly designed LED backlights and overdrive the LED dies to the point of thermal failure. It is not uncommon to have 4 or 5 LEDs randomly die on a 12 LED strip backlight because the TV manufacturer decided to integrate a power supply that provides too much current to the LEDs. I would not be surprised if a class action lawsuit is near for a few manufacturers.
In terms of the repair, there are a few things you can do:
- Take apart tv and observe power supply board (Be very careful, charged capacitors can be lethal)
- Look for any bulged capacitors or back spots. If you observe any of these conditions, your power supply may have failed instead of the LEDs
- Take entire tv & LCD assembly apart and replace led strips or LEDs on the LED strips.
Here are 2 related videos:
The reason why Vizio told you to buy a new TV is because the LEDs which have failed are the hardest part to get to inside the TV. It requires you to disassemble the lcd display assembly, which is very fragile. In order to disassembly the display assembly, you need a lot of space and a lot of patience.
Also, even if you replace the LEDs or LED strips, it is extremely likely that your backlight will fail again within 2 years. A lot of the folks who repair LED TVs mention to go into the settings of your tv and manually turn the backlight of the LCD at least half way down. Lowering the backlight brightness will increase the lifespan of your backlight.