I have a wonderful 12" macbook which had a bad key. i got a new keyboard from china (first one only the power key seemed to work) this one does fine until i literally screw the bottom case screws on. then it does what the first one they sent me did, power key works but nothing else responds. i unscrew the bottom open it up and try again and everything works again, until you try to screw the bottom back on. i imagine something is shorting it? i see there is a metal ground looking perimeter which the original black foil covered but may not be doing so well after removal, so i kaptan tapped it along the bottom near the trackpad where it seemed exposed just in case that was it but still no total solution. any ideas?