Grey/white screen after digitizer/lcd replacement?

I have had plenty of experience with fixing i-devices. Today, my sister spider-webed her white ipod touch. Luckily, my usual order from www.smartphone-parts.com had just came in, so I had the part to fix it. I replaced it with an aftermarket light blue colored screen. After I finished the repair, the device powered on and worked properly. I even made sure the cameras were fully functional. They were. So I set the ipod under a couple of books so the adhesive would set nice and strong. 10 minutes later I took the books off to check the adhesive, and when I pressed the power button to turn on the lock screen, the ipods screen lighted up, but it was gray with no picture. I dont understand. It worked perfectly fine! Could the lcd have really gone bad that fast? Please help.

Also, I did manage to loose the spring in the top right hand corner of the ipod by the rear facing camera, but Ive heard that has no affect.