Three techniques for creating boot media for a clean install of OSX. Article based on Yosemite. Keep the installer from being deleted Like all recent versions of OS X, Yosemite is distributed through the Mac App Store. As with the Mavericks
Failed on Mac Mini – possibly due to Sophos AV….. Searched….. and found….. http://www.iphonehacks.com/2016/09/fix-macos-sierra-problems.html 10 Most Common macOS Sierra Problems and How to Fix Them #1. macOS Sierra Upgrade Shows “An Error Has Occurred” Or “Failed to Download” This is
Boot into Recovery Partition If the above methods don’t work for you, then try resetting your admin password via the recovery partition. 1. Boot to the recovery partition on your original drive by holding down Command-R during the startup process.