White Screen After Screen Replacement

I have a white iPhone 4 model number A1349, which had a broken screen. I replaced the screen and after putting it back together it only showed a white screen with vertical black lines going across. I got the screen exchanged and the new screen also came out with a white screen. I thought i had screwed up for the second time but after the 3rd attempt, same problem occurred. I also have another att iphone 4 which would not turn on, so I decided to test the mother board with my white Iphone and only connected the charging dock and screen ribbons. The Att motherboard worked ( what a relief) and the screen showed a battery charging. So i take off the att motherboard and install the original motherboard from the white one the screen goes back white but on the other motherboard it works fine. Oh and i also fixed the power button.

What i have tried so far.

- Holding the sleep/wake button + home button for 10 seconds

- I connected it to itunes and was detected as in recovery mode and it restored it.

Nothing has worked so far! I have noticed that the screen goes black but in the center its and oval light with black and blue lines going across.

Any suggestions? The screen works on another motherboard why not this one??