My recollection of the previous videos in this series are that Dave focused on the column drivers. Could vertical stripes like this be caused by leaking row drivers?
It looks so. Since the whole panel is affected all row driver ics beeing bad is unlikely. So I don't think the actual panel or the row or column drivers are the problem.
It could be a bad connection somewhere between the TCON and the panel or a failed voltage on the TCON board.
@ Dave
Look for a negative voltage on the TCON board or on the LCD panel. Maybe it is labeled VGL or GOFF.
It is usually generated using a charge pump near the main boost converter on the TCON board, because they tap of the signal from the switching node.