I have a 1 year old Dell M170 and it has vertical stripes on the laptop LCD screen but the external always works fine. I can sometimes get it to work by closing and opening. Running diagnostics, it failed to detect the LCD inverter and I get: “error accessing LCD inverter” and code. When I look up the code with Dell they say it’s either the cable, LCD inverter or motherboard but nothing about the LCD itself being bad.
I have no idea how the inverter board can cause this problem. LCD inverter acts like a power supply for the backlight bulb, it converts low voltage DC power into high voltage AC power. When the inverter board goes bad you lose the backlight but to the best of my knowledge a failed inverter board cannot cause vertical stripes on the screen.
Motherboard problem? Possible but I doubt it because the external monitor works fine. When you have a faulty video card the same defect usually appears on both internal LCD and external monitor.
Sometimes you can get it to work by closing and opening the display. When you open or close the display you flexing the video cable. It’s possible the vertical stripes appear because of a loose connection somewhere inside the display assembly. You can try this. Open up the display assembly and reseat the video cable on the back of the LCD screen. It’s also possible that there is a loose connection between the video cable and the motherboard/video card, reseat this connection too. If reconnecting the video cable doesn’t help, I would try replacing the video cable.
If replacing the video cable doesn’t help, I would assume you have a faulty LCD screen.