I looked at this model and there is no free service manual so we can't see what it says to do. Also, does not appear to be a model LG lists here at lg.com
PS. I have yet to see any TV tech here offer diagnosis.
i've been having a problem with my LG 79UB980T, there's no picture visible in all the inputs (only vertical lines with flickering), tried satellite receiver, Xbox One & PS4. even the youtube and Netflix apps show menus but no videos, I can see the menus with full colors and listen to sound perfectly....
I use only high quality hdmi cables.
I thought it might be a burnt board at first but the TV worked perfectly for two days after changing it's location (weird i know), then the vertical lines came back.
What could it be?