Guide on this article is about how to root with Windows operating system and unlock the bootloader via mmmeff’s EZ-Unlock app.
1. First of all, download USB driver for Samsung Galaxy SIII from this link.
2. Extract the package to any folder.
3. On the phone, enable installation of third-party apps (Settings –> Security –> Unknown sources, near the bottom in the “Device administration” section)
4. On the phone, enable USB debugging (Settings –> Developer options –> USB debugging)
5. On the PC, make sure you don’t have any other Android devices connected, any Android emulators running, or any Android tools running. Plug your phone into a USB port on your computer. For best results, use a port directly on the machine, and not a USB hub.
6. Download RootDebugFS from this link.
7. Double-click RootDebugfs.bat and follow the directions on the screen. Your phone will reboot 3 or 4 times during the process; just leave it plugged in. To be safe, don’t switch to any other applications while the root process is running.
8. Download the EZ-Unlock app from Play Store or from this link.
9. Open the app and select unlock. Now your phone is unlocked.