Trackpad and Keyboard not working

Hello.

I'm in a bit of a pickle. Recently my Dad has been complaining about sensitivity issues with his trackpad, so I set out to adjust the screw; all was well up to this point. While I was reassembling everything the Flex Cable into the trackpad got yanked out. I reseated the cable on both ends, reassembled the machine and wen to fire it up. When it booted up the trackpad and keyboard were unresponsive. I striped it down again and checked the connections and all was fine. Fired it up again and all it would boot to was a gray screen no apple logo. I borrowed my Mouse and Keyboard from my Hackintosh Build and tried to use it to PRAM reset and boot to recovery..etc but nothing will get past the gray screen. The only way I can get it to boot is by {unplugging the battery-hitting the power button few times-reconnecting the battery} this will get me to the desktop where I can use my USB mouse and keyboard only. None of the cables appear to be damaged. Im stumped!

Be grateful to any help

Thank You.