I have a LG tv model 50LN5100-UB. The picture went out. I did the flashlight test and saw the menu screen. I replaced the power supply/ LED board but it didnt fix the problem.

Over ther:SHARP RUNTKA903WJQZ QPWBS0398SNPZ(1Y), PSD-0863 POWER SUPPLY BOARD
https://www.abctay.com/original-sharp-runtka903wjqz-qpwbs0398snpz1y-psd0863-power-supply-board-p-1087.html

Back - light problem. Check and replace damaged component/s at its back-light inverter board, or replace this board as card basis. If you wish to get some details; check the site linked here. Surf the site with patience. Pull up older posts. It will be best to replace the inverter board as card basis.
http://electronicshelponline.blogspot.com/
To some model sets; especially LED back-lighted types; the back-light inverter circuit will be part of the main power supply board [SMPS]. In such cases, the power supply board might need replacement. To some models sets, the back-light inverter and SMPS section circuit will be integrated at its main board itself. If so; the main board should be replaced. To some models of sets, all these section circuit will be integrated at its main board. If this is the case, you have to replace the main board.