I replaced the lcd digitizer assembly in a nexus 7 first gen. Everything worked fine so i set the screws in and hit the power button only to have an array of colors. Disassembled and checked lcd ribbon cable. everything was fine so i power it up and it worked! set the screws in AGAIN and now i have nothing but a black screen. i disassembled it and still a black screen. I tried all the power button tricks and now i am at a loss