That sounds like a hardware failure which can be display, connections to/from the display or the main board.
I've seen it be all these parts over the years so the sad news is that it's rarely the same thing from one machine to the next.
However my old friend's advice is this. "Replace the cheapest part first." when you can't guess which one.
Finally, did you do the old unplug and plug in each connection routine?
Since last Friday, small horizontal lines started appearing on laptops screen. They are completely random mostly shows up on solid white, on some types of text or image borders. Other thing is random screen flickers, for maybe third of a second screen or half it turns blue.
I think it's not a driver problem, tried updating, downgrading them, no difference. Tried cleaning it and changing thermal paste. Didn't help, but at least temps are great now... Tried connecting to other monitors, problem doesn't transfer (only tried HDMI).
But while putting it back together, I've found out that screen is normal while laptop isn't completely screwed together. Other thing I noticed that problem intensifies while plugged in to a wall, and it get's even worse if I apply pressure, roughly around the place where power and monitor cables connects to a motherboard.
I think it's probably issue with screen cable and not worst case scenario, fried graphics card. So I would like to hear other peoples opinions about this problem. And if my poor laptop, his name is Kemosabe and he is 3years old, would survive at least three weeks until I can get it to repair shop?
Sorry for bad English and thanks in advance.