iPhone 4 Right half of the screen is white/grey after repairing?

Today I broke down my iPhone 4 and replaced the battery and lock button because they were both malfunctioning. After I assembled it all back together, (twice) double checking everything to make sure it was correct, the right half of the screen is whiteish/greyish. It is still functional to touch but I can't seem to figure out what I did wrong. I checked the LCD connection to the logic board and it seems to be okay. Could I have damaged something? By the way, I couldn't fix the lock button. I need to buy a whole new power and sensor cable.