IPhone :: No Screen Image

I built a "frankenstein" iphone out of the parts of a number of broken ones and today was the first-run power up. Happily, most things worked. Then, I tried to pull it apart to fix the minor issues and that's when things went bad. When I lifted the digitizer with a suction cup, I had forgotten that it was not totally adhered to the LCD frame. It had a little bit of adhesive at the bottom and a little at the top, but it separated when I pulled. I put an adhesive strip on the bottom part and let it connect the two so that I could lift the assembly out. I'm guessing in the process of this I strained the ribbon cables, but read on, because its not that simple.

I adhered the pieces and reconnected everything. When I put it back together, the screen didn't light up when I hit the power button. The phone is still on, it still makes audible alerts etc but no screen image. I tried connecting another screen (not connected to rails, digitizer etc) and hitting power and still nothing.

Keep in mind all of these parts should be working, but this phone is built from the ground up. Every single piece was installed into a new frame separately, but it did work when I first put it all together.

Just tried my screen on a different iphone. Works fine. So its the phone, I guess. What could cause it to stop outputting an image just like that?