Reinstall macOS High Sierra to resolve Mac won't boot issue. The last method that you can try is to download macOS High Sierra and create a new bootable drive to clean install macOS High Sierra on Mac computer so to make it boot up normally and work smoothly again. The final release of macOS 10.13 High Sierra is now available to download as of September 25, 2017. Leading into this, some Apple fanatics opted to install macOS 10.13 High Sierra early via. In that case you need to find a Mac that's running an older version of the macOS, log into the Mac App Store with your password and download High Sierra's installer.
The official way is to use the Mac App store, but that only works if you ever downloaded High Sierra in the past. Here's how I got mine: Look up DosDude1's High Sierra Patcher (even if you don't need the patcher part). Download the Patcher Application. How to Download Apple Mac OSX 10.12 Sierra? Apple recommends downloading the High Sierra OS from the Mac AppStore. It is recommended to download the High Sierra due to security and compatibility reasons. During installation, your Mac might restart many times. It will then perform some initial setup tasks in the background.
You can upgrade to macOS Sierra from OS X Lion or later on any of the following Mac models. Your Mac also needs at least 2GB of memory and 8.8GB of available storage space.
MacBook introduced in late 2009 or later
MacBook Air introduced in late 2010 or later
MacBook Pro introduced in mid 2010 or later
Mac mini introduced in mid 2010 or later
iMac introduced in late 2009 or later
Mac Pro introduced in mid 2010 or later
To find your Mac model, memory, storage space, and macOS version, choose About This Mac from the Apple menu . If your Mac isn't compatible with macOS Sierra, the installer will let you know.
Before installing any upgrade, it’s a good idea to back up your Mac. Time Machine makes it simple, and other backup methods are also available. Learn how to back up your Mac.
It takes time to download and install macOS, so make sure that you have a reliable Internet connection. If you're using a Mac notebook computer, plug it into AC power.
For the strongest security and latest features, find out whether you can upgrade to macOS Catalina, the latest version of the Mac operating system.
If you still need macOS Sierra, use this link: Download macOS Sierra. A file named InstallOS.dmg will download to your Mac.
Double-click the downloaded file to open a window showing its contents. Then double-click the file within, named InstallOS.pkg.
Follow the onscreen instructions, which will guide you through the steps necessary to install.
After installation of the installer is complete, open the Applications folder on your Mac, then double-click the file named Install macOS Sierra.
Click Continue and follow the onscreen instructions. You might find it easiest to begin installation in the evening so that it can complete overnight, if needed.
Please allow installation to complete without putting your Mac to sleep or closing its lid. Your Mac might restart, show a progress bar, or show a blank screen several times as it installs both macOS and related updates to your Mac firmware.