My win 10 pro downgraded last week and become non genuine. originally i had home installed and upgraded via a popular online site for "E" licences, cheap, cheerful and ok, till last week. contacting the seller got no results as did nothing else. It;s a complete re install as win 10 will not self downgrade as we all know. A workaround by chance appeared. I simply re signed into my microsoft account on said device and re checked for updates and voila activated once again, now i have signed out again. I never keep a machine signed into msoft, no matter how much i am promised. Thank the lord for smaller than small mercies as i had scraped all my data from said computer and was about to re install via flash drive a home edition...which probably would have just over installed pro once again after the pre install sign in process i suppose.