We have published a method to root the Galaxy S3 before on this site, but many of you have been inquiring how to remove root in order to support OTA (over the air) operations once again and update to the most current firmware. If you used the method described in our website, then you already have root and are running stock firmware, which is the ideal situation. If you are not running stock, you will need to flash a older stock firmware in order to update to the latest OTA firmware.
In this tutorial I will show you how to reset the flash counter and remove the custom binary flag which is what stops your device from updating, even though it’s running stock firmware. It’s a fairly simple process, but as usual you should be aware of the risks of bricking or damaging your device that always come with these situations, and that we cannot take responsibility for this.
So, the first thing you should do is to confirm your current situation. To do this, simply turn off your phone and hold the Volume Down, Home and Power buttons and then pres Volume Up when you see the warning, and you will boot into Download Mode. Then, you should take note of the text in the upper left corner of your screen. If you see “Custom” in the “Current Binary” and “Yes” after the “Current Binary Download” section (plus a counter), take note of that info and proceed.
Then, reboot your device. While it boots go to this link and download the latest version of TriangleAway attached to the bottom of the post, and take a chance to read the information provided, making sure your device is on the supported devices list (check your model carefully)! After the phone boots and you have downloaded TriangleAway (the .apk file), transfer it to your phone and install it (use a standard file explorer to find it on your phone or SD card). After it installs, allow it to obtain SuperUser permissions and you should see a screen similar to this:
Make sure the info under “Current status” is the same you saw during Download mode. If it checks out, press “Reset flash counter” and press “Continue” if you are ready to begin. Let the app do it’s thing, and your phone should let you know that the flash counter has been reset and reboot automatically (do a manual reboot if it doesn’t reboot after the operation).
Then, go back into Download mode (don’t use TriangleAway!) and check the info on the upper left corner yet again, and you should see “Custom Binary Download” set to no and “Custom Binary” set to “Samsung Official” (or similar values). If this is the case, it means TriangleAway did work and you should now be able to do OTA updates when you boot your phone. Be advised that this may only temporarily work, so check OTA right after you boot your phone and update to the latest version of your firmware.
There may be certain cases where this procedure will not work (that is, TriangleAway will reset device status but OTA will not work, or the info in Download mode will not be correct), and in those cases flashing the stock firmware and wiping data right after this procedure will be the preferred solution (check under Settings>About Device>Status>Device Status to see if your device still detects as modified). If you need a tutorial for that, let me know in the comments and I will do so as soon as possible.