XPS M1530 Displays on external monitor but not LCD?

Hi I'm new here so im not sure if there was any protocol before posting, but i've been working on my laptop for almost 2 weeks now and no one has been able to help me yet, but it looked like there were tons of helpful people here so I figured its worth a shot!

So my problem is that my laptop will display perfectly fine on any external monitor, but not on my LCD screen. I originally replaced my old screen with this new one because it had vertical lines, but it still worked. I got a replacement screen that I made 100% sure it worked (had them show me in the shop that it was fine)...so I get home and plug it in..works perfect. I turn the computer off and finish installing and putting everything back in place..and now it is completely black. I went to device manager and looked under monitors and it doesnt even recognize this screen.
So I switched back to my old screen to test it out, and it doesnt recognize that screen either. I thought maybe it was the LCD ribbon cable that needed replacement, so I got a brand new one from the shop which they also tested for me to make sure, and that still hasnt solved my problem.
I've searched for a week now online to find someone with the same problem to no avail.

Any ideas?


PS: I just came back from taking it in again the new screen still works when they run tests on it.

Any info would be greatly appreciated!

 

wow, so get this...I plugged in my old Chi Mei screen and at start up toggled the fn+F8 and got the screen to come on, but still really dim...I unplugged it and plugged in my new LG one, and it comes on! only its really dim....and if I go to device manager and look at the details of the monitor, it still recognizes the screen as the chi mei.....

Also..if I start up my comp with this LG and try to toggle fn+F8, it doesnt work..only if I plug in the chi mei first....I dont understand....

 

So...this is kind of funny...check this out. After so long of messing with it..I finally got bored and looked at every tiny detail of the lcd and computer till I found one little anomaly...this one pin that the ribbon cable plugs into..so tiny..couldnt see it with the naked eye...was slightly bent. I took a super thin needle and nudged it a bit back in place...screen works perfectly fine. That would have cost me 200 dollars at a repair shop hahah.

Heres a photo of it, I had to zoom in really far with a macro lens then zoom in on the photo to actually see it.