No need to go to any Apple Center or third party repair center for the cable. You need part: A1502 2015 821-00184-A and it is all over the internet. try a few sites. They are made in China, the US and in Europe and they should not cost you more than 5-8 USD depending on the country. You put them in yourself within 10 minutes. The problem mostly start out with failing keys. This happens when you wake up your computer or restart it and than the issue moves to your trackpad. Try connecting it to an external screen and close the lit. If you don’t you still might experience problems with your external Bluetooth keyboard. I have had the problem on more than one computer and the problem mostly started after replacing the battery or when an older battery was slightly bloating. You fte cannot see that the cable is damaged. it looks all fine at inspection.