I have an LG OLED TV with the same issue. I didn't think to try the input cables, so I tried, and found the same thing. Click, power on, lines. The lines make it look like the panel is shot. But, I'm not sure what it means that when the cables are reattached, the display refuses to turn on entirely. [br]
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Sorry that I am just now finding this. I also have no financial commitment to this TV, but I wonder if a new cable would help. Were you ever able to find out anything new regarding this?