I down loaded the graphics driver for my dv6000 and installed it but a message came up that nothing was changed due to none of them had to do with my hardware. Then I went to HP and had them detect my model and it downloaded the latest driver and installed them but my external monitor is stlll missing the red color. I also tried it on a HD tv and it looks the same as the monitor. I believe like you that the graphics output on the MB is bad. But why not on my laptop screen. Having been a tv repairman, this looks like a bad connection after the graphics chip.
I would take the back off and check it but not sure how many of the screws need removing. Does anyone know? Even those in the battery slot should come out, right? I count 14 screws plus the ones under the battery. Anyone have a sketch that shows the screws to remove to take the back cover off?