The explained steps in this Guide will help you to Factory Reset Samsung Galaxy S3 with model numbers:

1- This process restores the Android platform to its original state and wipe all your data, So backup all the wanted data (Contacts, SMS, Photos, Videos,… Etc).

To Update Samsung Galaxy S3 GT-I9300 Software you need to install a newer firmware version on it. You can update your Samsung Galaxy S3 GT-I9300 without a computer by going to Settings > About Device > Software Update. Also, You can update this Samsung device manually, But you need to use a computer.

In this Guide, You will learn how to update Samsung Galaxy S3 GT-I9300 manually by using the Odin3 flasher and Samsung Stock Firmware files.