I have now been at it for 2 days & cant get Sierra to install on Mac Mini mid 2010 , although Apple states that is will run. I keep on getting various error messages. I have tried downloading os installer form Apple website , from other websites , and still no luck. It keeps on telling me things like :Cannot be installed on this computer / or it stops 2 minutes from finishing installation / an error message that suggests that the clock is wrong , which it isn't & a whole host of other errors I cant even remember while trying different options. I'v tried direct installation , installing from boot usb , nothing seems to work. I'm trying to install sierra on another partition as I need to keep os 10.10.5 running as well. Can anybody assist me please!!! Thanx!!!!