- Only flash this stock ROM if you have the same model number corresponding with the title (SC-06D) or you will soft-brick your device and get stuck in a boot loop. You can check your S3’s model number by tapping on the Menu > Settings > About Device > Model Number.
BEFORE WE BEGIN
- You are regaining any warranty you might have left by unrooting and flashing the stock ROM on the Samsung Galaxy S3. Just be careful when shopping for your next smartphone if you are still planning on shopping with Samsung as the later models now have Samsung’s Knox security. It’s usually when you are buying one of the flagships, or just the popular models.
- Enable your S3’s USB Debugging Mode by tapping on the Menu > Settings > Developer Options > USB Debugging Mode.
- Download the Samsung USB Drivers  to your computer before you start the steps.
HOW TO ROOT SAMSUNG GALAXY S3 SC-06D DOCOMO
- Download your stock ROM for the S3 DoCoMo variant from this link  directly to the computer.
- Download the Odin 3.07 from this link  directly to your computer.
- Right-click over each of the files once they are on the desktop of your computer and choose the “extract here” option.
- Double-click over the executable Odin flash tool file to get the program opening up on your desktop.
- Boot the Samsung Galaxy S3 DoCoMo in download mode . See also: How to fix Samsung Galaxy S3 stuck in download mode .
- Plug your Samsung Galaxy S3 smartphone into the computer with the same USB cable you normally use to charge the battery of the device.
- The Odin flash tool should give you the added message from the user-interface and the ID: COM box should light up a green color. That’s how you know the USB Drivers are working. Those who have installed the drivers but do not see the green box or added message should try rebooting the Windows computer and see if that helps.
- Click the AP or the PDA button you can see from the Odin app on the computer and upload your rooting tar file from the desktop.
- Leave the default settings in the Odin app the same way they were when you first opened Odin. You can always download a fresh copy of the Odin flash tool if you cannot remember what they are for your application.
Click the Start button and the rooting exploit for your S3 DoCoMo smartphone will be applied in a few minutes.
- Wait until you get the mass message from the Odin app and your device reboots before unplugging it from the computer.
You can download any of the root checker apps from the Google Play Store if you need to find out if it worked before installing your root-requiring applications from trusted sources online.
Try installing Odin 3.09 or Odin 3.10 if your Odin 3.07 is not flashing your stock ROM on your device. Sometimes you need to change up the version of Odin you are using with your device. Correspondingly, those of you who do not get the device detected by Odin should try getting the USB Drivers to work instead.