White screen at power up

I have an ipod 4th generation. screen worked fine. Then replaced the rear facing camera, and now the screen only lights up white. The ipod is still operational because I can hear the usual ipod sounds and itunes will see it, however, the touch screen does not work either (tried to swipe to unlock even though I couldnt see the bar. no sound was made to indicate it unlocked.)

Which of the two ribbon cables handle the backlight and which the display? If I knew that, I could trouble shoot further.