Thank you very much this was extremely helpful! I had the same issue with my iPad 2. I replaced he digitizer and my LCD seemed to stop working after I replaced the cracked screen. I assumed that I had cracked the LCD during the removal of the screen. I purchased a new LCD but it still did not work. After reading your answers, I realized what the problem was. I turned off the iPad and then turned it back on and vuala it worked just fine.