Well, initially if there is no image, but there is sound, then TV is ok. Only backlight not working. Definitely, change the LED strips. Also, remove artificial aging details. Current limit resistor to lower the backlight curren, сheck and change capacitors at the output of the driver - if there are ripples, the led diodes will burn out again. This upgrade goes against the marketing... engineers calculated when the detals would fail. The magnitude of the supply voltage ripples in cheap TVs go off scale due to the use of simple circuit solutions and incomplete and cheap piping and not quite high-quality applied element base. Improve power quality - extend service life and noticeably improve picture quality. Good luck.