How to fix a multi coloured line down the middle?
it like a rainbow that comes and goes
max, if the width of this line is about one pixel wide, it is most likely a TAB error. Very difficult to repair if at all. Sometimes just applying some pressure to the tab may resolve it. If you have multiple lines, it could be the T-con board. Since we cannot see what you see, I suggest that you attach a couple of images with your question.