I have an hp laptop. The screen is unreadable when it is turned on. Tons of squiggly horizontal lines. I get a clear perfect picture on an external monitor when I plug it into the laptop. I have replaced the screen, the inverter and the cable connecting the screen to the laptop. None of this has changed the outcome. I get exactly the same result on the laptop screen. From what I understand it can't be the video card, which I'm assuming is part of the motherboard given it is a laptop, since the external monitor shows a perfect image. Any help would be appreciated.