I see that this is still a huge issue with most and I did have success fixing it. As I mentioned in a previous comment, I tried cooling the system to see if it was swelling battery, it was not. That led me to purchasing a ribbon cable off Amazon. To replace the cable you need a 5 point pentalobe screwdriver to remove the back cover. The job took 10 minutes to complete. Its now been over a month and have had 0 issues. Hope this helps :)

OK, have the fix for you and its a simple one! First, I will rundown my issue so there will be no question as to what the issue was! Started off by randomly losing my keypad and trackpak, mayby once a few weeks. It gradually became worse to every day and having to reboot the Mac to sometimes get it back, sometimes it worked, some times it did not. Eventually i had complete failure. I reformatted my drive and installed a fresh OS, didnt work. I checked my battery with Coconut to see if it was ok, and it was. I tried the fridge method to see if I had a swollen battery, did not change. Finnaly i decided to order the trackpad ribbon cable, to me it was the only thing that made any sence since it wasnt a software issue, or a hardware issue. I ordered the cable from Amazon for a whopping $12.00 CAN and had it in 4 days, installed it and man do ever like using my keypad and trackpad now!!!!! Works great and right away. Saved my self 400.00 from taking it to Apple. Below is the link if you like! Tools required - 1...