Our LG 42LN5400 42” tv had a black screen but audio was still working. I researched and found out that the back light LEDs are usually the problem so I ordered new ones and replaced them. Apparently that was not the problem because it is still a black screen with audio. I’ve tried to test the main power board and it seems to be working as well. Does anyone have any ideas on what else it could be? I’ve already invested money into the LED lights so I’m hoping to still find a fix for this problem. Thanks!