@griseldaro96114 the problem with AI generated answers is that the AI makes stuff up, that it does not know.
T-con boards and main boards are never the cause for horizontal lines. Those are strictly limited to the LCD driver boards and/or the panel. Some combination of horizontal lines with other abnormalities on the display can come from the motherboard. You did obviously not have those lines before you change the power board. We will need to know if this is a new board or used and if it is an identical board. Also, please verify that your TV is a QN65Q7FAMFXZA
Post some good pictures of what your screen actually shows, all of your boards and how the ribbon cables are connected to it etc. Those pictures need to be large and well focused. Adding images to an existing question
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