There are horizontal flashing lines running across the laptop screen. The laptop starts fine and you still can see the picture, but there are flashing lines running across a part of the image.
1. Video card failure.
2. Bad connection between video cable and LCD screen.
3. Bad LCD screen.
4. Faulty video cable.
Possible troubleshooting steps and repair solution:
1. First of all, test the laptop video output on the external monitor. If you see same flashing lines running through the image on the external monitor, you have a problem with the video card. If flashing lines appear only on the laptop screen, the failure is not related to the video card.
2. Just in case, try re-seating the video cable connectors on the motherboard/video card and maybe the back of the LCD screen. It’ s not likely but possible that connection is loose and reconnecting the cable will fix the flashing lines.
3. If re-seating the cable connectors doesn’t help, most likely you have a faulty LCD screen. The LCD screen has to be replaced.
4. If replacing the screen doesn’t help, try replacing the video cable. It’s very unlikely that this problem is related to the video cable but there is a slight possibility of that.