WARNING! Master resetting your smartphone will result in the deletion of all personal data stored on the phone's internal memory. This includes ringtones, downloaded content, media files, contacts, apps and so on. However, data stored on the SIM and SD cards will not be removed.

NOTE: Before factory resetting your smartphone you may want to learn how to back up the data on it. Visit this link for a full guide on backing up data on the Galaxy Grand Max, and this link for a guide on restoring data.

Master Reset via Settings:

1. From the home screen, tap "Apps"
2. Go to "Settings"
3. Swipe to "User and Backup" and then tap "Backup and reset"
4. If you want, clear the check boxes next to "Automatic restore" and "Back up my data"
5. Tap "Factory data reset" > "Reset device"
6. If your smartphone is protected by a lock screen, enter the password / PIN / pattern and tap "Continue"
7. Tap "Delete all" to confirm

Master Reset via Recovery (Hardware Keys):

NOTE: In case you are unable to master reset the phone from the settings menu, then you might be able to do so from the recovery menu. It can be accessed after pressing a combination of hardware keys which reset your device into recovery. To do so:

1. Turn off the smartphone
2. Press and hold the "Home", "Power" and "Volume Up" buttons simultaneously
3. After the phone vibrates, release the "Power" button but continue holding the other two keys
4. When the "Android System Recovery" screen appears, release all hardware keys
5. Use the "Volume" buttons to navigate the menus
6. Use "Volume Down" to highlight "wipe data / factory reset"
7. Press the "Power" key to select the highlighted option
8. Highlight "yes -- delete all user data" and press "Power" again
9. Once the phone resets the storage, it should display "Reboot system now"
10. Press "Power" one last time to reboot your phone

Update the Android OS:

NOTE: Some software updates that you have applied prior to the factory reset may be lost, so it's advised to check for software updates after you apply the reset. To do so:

1. Ensure that your smartphone is connected to a Wi-Fi network
2. Go to the phone's "Settings" menu
3. Swipe to "About device" and tap "Software update"
4. Press "OK", and in case an update is available, follow the on-screen prompts to download and apply it