I was working with my LinkIt 7688 Smart Duo connected with USB cable. Arduino sketch upload worked fine until I changed board in menu. After that connection with the board disappeared. I restarted my 7688, my laptop, updated firmware and boot loader via Web interface, remove Arduino software and repeated steps from "Get started..." manual.
But this time I have not seen "Driver successfully installed message".
* can't see Ports section in Device Section when I plug my.
* but I have Unknown device (Device descriptor request failed) under USB controllers in Device manager.
Any idea what could it be? Any advises how can I diagnose source of this issue? It looks like diver issue but due to lack of experience I don't know what could happen.