Before one tries to fix a black screen on LED TV. It's most important to evaluate the conditions of the TV. There are some test cases one can perform to evaluate the problem. Follow the below steps.
1. Turn on the LED TV from the main power board.
2. Do you find the indicator light glowing? // If Yes, You have the power supply for the TV. //
3. Turn On the TV with an infrared remote?
4. If the TV didn't turn On, check if the infrared remote is functioning properly from here.
5. If the Infrared remote is working and you still can't see the picture. Try to play something on Tv and check if you have audio output.
6. If you don't have audio output while trying to play. There is a chance that the motherboard or logic board might have gone bad. A qualified technician needs to see your LED Smart TV.
7. If you have the audio output but still no display. You can confirm, no failure in the logic board, and proceed ahead with steps.
8. Take a torch and try to show some light towards your screen. If you find pictures on the screen. It is confirmed as Backlight Failure.9. If still no picture on the screen, It is recommended to get the television checked by a qualified technician.