Before getting parts, you must diagnose.
The backlight is fine as told.
What I would do is open the back cover, and carefully, with power unplugged, first visually check if there is any bulged electrolytic capacitors; that is a confirmed common reason to create problems of all sorts. If none appears bulged disconnect ALL cables interconnecting boards and the LCD panel, inspect, clean and refit. There is several types of connectors for ribbon and foil cables (slide and lever locking) that will break if you do not handle them properly.
Retest and come back.
There is plenty of pictures of bulged capacitors on the web to recognize them as failed, and also of complains about vertical lines.