LED strips sit behind the LCD panel and provide the light the picture is filtered through. When one or more strips fail you get dark bands, a dim picture, or a set that flashes once and goes black.
Strips are matched to the panel size and layout, so buy by the strip part number and confirm the connector and strip length. Replacing strips requires removing the panel, which is best done on a clean flat surface with the set fully discharged.
If only one strip is dead, replacing the full set is still the safer repair, because the remaining strips have the same hours on them.
