I've just tried to repair my keyboard's usb cable as it has been damaged right where it goes into the keyboard. I've cut out the bad part of the cable and reconnected the wires. I've tried it and all is working well but I've used tape (lots of it :D). So it is possible that at some point the wires inside the USB cable will mix and my question is what is the possible damage due to that. For example is there a possibility of a short circuit damaging my motherboard? I've read somewhere that USB 2.0 and above needed to have short circuit protection as a standard, but I wanted to ask just to be sure. Thank you!
USB ports should be capable of surviving short-circuit, but unfortunately, there are motherboard manufacturers which interpret the standard in different ways. Some will simply turn off the port, others will allow limited current to go through the port, some will have no protection at all.
Unfortunately, if you're the owner of one of the badly designed motherboards, there's no safe way for you to test what would happen.