One of the 3 lcd ribbon connectors is loose. I just replaced my battery and had this happen, twice. Looking at the circuit board from above with the home button closest to you (south), the 3 LCD ribbons are plugged in from the screen to the board at the NE corner( nearest to power button). They are tiny thin strips in this configuration: l_l They are under a silver square cover with 4 tiny screws. The problem is, when you re-attach the cover, you need to lift the screen closer to 90 degrees in order to screw in the 4 screws. Since there is very little play in the ribbons, the left ribbon plug comes out. It is hard to notice because this ribbon/plug is below the other 2. I tried twice and ended up leaving the cover off. Works fine (but I'll save the cover and 4 screws just in case).