Vertical lines on left half of screen

A couple of days ago lines appeared on my Hitachi 48” tv screen (48hk6t74u). The lines are on the left hand side (as I sit facing the tv). There is one thick black line next to coloured thin lines from top to bottom of the screen. It is only a couple of inches wide in total. After looking a videos online, the general consensus was that it was the display ribbons or the T-Con board. I swapped the ribbons over to check if this was the problem and the issue was still in the same place. I then replaced the T-con board with a new one. Unfortunately, this has not fixed the problem and the lines are still there. When I take the ribbons out, and turn the tv on, the screen is completely blue. Then when I replace them, the picture is fine apart from the same lines on the left half of the screen. Does anyone know what the issue might be and is it fixable?