XPS M1530 LCD/GPU Issue

Here's what I have-a Dell XPS M1530 with a busted LCD. The screen use to display, but I hooked up one from an Inspiron 1525 (same connector), and now the backlight works, but only displays white. First picture.
When hooked to an external, the display is fine on the external (second picture). But the laptop LCD is still white.

So my question is-Do I have a faulty GPU, Screen is bad I know, or cable? Why would it just stop displaying after hooking the other LCD??? I am lost on this one and don't want to spend $100 or more for a screen if the mobo or cable is bad. Would like to narrow it down to exact problem. Any clues or ideas???






And both together----

 

OK????? Bump!!!! Was hoping to get a response. Seems to me the card is good. I just have to figure out why the LCD will only display white. HELP!!!!!!!!!

 

It looks like your laptop LCD is totally damaged and would need replacement.
Your GPU seems fine. Try a videogame to see if it crashes.

 

Thanks for the reply. Didn't try a game, but I did plop in a new LCD and the issue is still the same. External video is fine still. Thinking it may be the cable???? Ideas people????