If it's the flex cable that you have to "insert" and then close the FPC then they are notorious for issue's. After you have a power flex on plug in the lcd and lay it so you still have access to the power flex. From there, open the FPC flap on the power flex and with tweezers wiggle it. Lot's of the time they need to be left out a little bit in order to work. If you get power and the click sound when pressing the power button do a hard reset.