Different kind of cable issue

I've had a weird problem crop up from last night. When I plug my watch into my PC it vibrates like it does when you plug it into a wall charger and it does charge. However the PC does not recognise it as a USB device and because of this Garmin Express does not see it so I can' sync it etc. When I go to My Computer it also doesn't see it as an external device like before. I have done a hard power off and also tried both Garmin and Mass Storage under USB mode in the settings. I have also tested using different cables and PC's , with the same result, so it seems to be the port on the watch. Could it be partially blown ?