How to unsolder USB ribbon and solder on wires from USB cable?

The USB on my Nike sport watch broke off, and i am unable to charge it at all.. so i saw a you tube video in which someone unsolders the usb ribbon and cuts off a usb cord and solders the wires in place (drills a small hole in the side) and i dont want to ruin the logic board inside the watch.. so i need advice.. im normally a handy person and i have some experience, but i dont want to ruin the watch... ADVICE IS WELCOME! thanks and have a nice day..

PS- i already called Nike my warranty is up so yeah..