I have the same issue - Screen won't display anything after replacing the screen and digitizer. However, I do hear a the charging sound when i plug the iphone to the wall. I check the connection. They seems to be all connected. However, i am not sure how to check that the 2 wires from the digitizer are actually connecting to the mother board. Are they supposed to snap into place? It's difficult for me to check if the wires are lined up with the mother board when I intall the mother board and battery back into the assembly. Any idea how to check this connection properly?