This LG 55UJ6200 TV turns on and has sound but has a black screen. The problem was one of the LEDS in the backlight was bad. After replacing the bad led it works like a charm. To do this repair 1. Take off the back assembly 2. Take off the front screen assembly 3. Tape the ribbon cable from the LCD to the back of the LCD panel 4. Use suction cups to remove LCD panel 5. Test all LED strips, take out any strips that are bad and fix them it helps to put them all in a row and do them all at once. 6. Re-install them and double check that they are all working 7. Re-glue the led covers 8. Re-assemble the TV. Essential Tools -Two suctions cups (https://amzn.to/2KF84r7) -Led tester (https://amzn.to/38lRq89) -New leds 3V (https://ebay.us/Z8fzol) Newsons Electronics Facebook Page - www.facebook.com/NewsonsElectronics WebSite -- www.newsonselectronics.ca You can also support me on Patreon -- https://www.patreon.com/user?u=47548239