He opened Terminal. With shaking fingers, he typed the command PolymerMom had provided:

Type the following command (replace MyVolume with your drive name): sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ Sierra.app Press and provide your password. Step 3: Run the Update Double-click the installer in your Applications folder. Follow the on-screen prompts. Your Mac will restart several times. ⚠️ Important Considerations

Before downloading, ensure your Mac supports macOS Sierra. Generally, the following models are compatible: : Late 2009 or newer MacBook Pro : Mid 2010 or newer MacBook Air : Late 2010 or newer Mac mini : Mid 2010 or newer iMac : Late 2009 or newer Mac Pro : Mid 2010 or newer Minimum Requirements : 2GB of RAM 8.8GB of available disk space OS X Lion 10.7.5 or later installed 📥 Step 2: Download the Installer

: For a full installer, you can sometimes access it via direct links from Apple Support that open in the Mac App Store. : Advanced users can use the softwareupdate command-line tool to fetch available legacy installers.

sudo /Applications/Install\ macOS\ Sierra.app/Contents/Resources/createinstallmedia --volume /Volumes/MyVolume --applicationpath /Applications/Install\ macOS\ Sierra.app --nointeraction