Difficulty Level: Advanced User. Required Time: 10 Minutes.

A Nandroid backup is a complete copy of everything that’s on your Samsung Galaxy. It is often used to restore the phone to a working state should you run into problems with your device. The difference between a regular backup and a Nandroid backup is that the latter does not only back up basic account data but also backs up everything else that’s on the device: the ROM, apps, settings, and all your files.

When you hack a Samsung Galaxy, creating a Nandroid backup before you do anything else is absolutely invaluable. In fact, responsible hacking cannot be done without it. So the first step to take before making modifications to your mobile’s operating system or before installing (called flashing) custom made firmware, is always to create a Nandroid backup. If you brick your device or if something else goes wrong, you can always reverse all actions by restoring from the Nandroid backup. This means you should create a backup every time before you make modifications!

One of the many ways to create a Nandroid backup is to use the app called ROM Manager, which you can download from the Google Play store. Note that you cannot restore selectively from a Nandroid backup (for example only apps). Restoring from a Nandroid backup puts the mobile device exactly to where it was right before you created the backup. If you seek to selectively back up things such as specific apps and their settings, consider a different app: Titanium Backup.

Before you start

Creating a Nandroid backup requires that you have rooted your Samsung Galaxy. If you are not familiar with rooting and its benefits, first read about it here.

A Word of Caution GalaxyUnlocker is not responsible for any outcome on your mobile device as a result of rooting, flashing, or hacking it. You are fully responsible if your device gets bricked, which can happen if you do not implement procedures correctly. Rooting, flashing, and hacking may void your warranty.

Step 1: Get ROM Manager

ROM Manager, an app developed by Koushik Dutta, is available as a free and as a premium version in the Google Play store. The free version is sufficient for creating and restoring from Nandroid backups. Before you use this app, check whether your device is supported by ROM Manager first.

Action: Install the app and open it.

Step 2: Create a Nandroid backup

Creating the backup is easy and completely automatic. The backup creates a 1:1 snapshot of the entire operating system.

Action: In the BACKUP AND RESTORE section tap on Backup Current ROM. Don't rename the backup because ROM Manager has not fixed this feature to this date. If you rename it, you won't be able to restore it later. Confirm with OK. 

Step 3: Complete the Nandroid backup

ROM Manager will now restart your phone and boot it into a special mode called Recovery mode where it makes all the changes.

Action: When the process has finished and before your phone restarts, you might see a warning message (on select Samsung models) saying “ROM may flash stock recovery on boot. Fix?” If you get this message, use the Volume down button to select “Yes – Disable recovery flash” and confirm with the Home button. This enables the phone to keep using ROM Manager’s custom Recovery. What’s that you say? Read on…

Good to know: A “Recovery” is a special mode that your phone can boot into before it boots the actual Android operating system. There are only a few things you can do with your phone when it’s in Recovery mode. It’s used primarily to flash (install) a firmware. And if you want to restore your phone to the state your device was in before it stopped working or if you just want to get back to the point before you made any changes, it’s the Recovery mode from where you can do it. While it’s possible to restore the backup from within the Android operating system, this won’t do you any good if your phone can’t boot into it anymore. The answer is booting into Recovery mode instead from where you can still control your phone. A life-saver! Samsung’s “stock” Recovery can only flash Samsung firmware but ROM Manager’s “custom” Recovery, called ClockWorkMod or CWM, can flash any firmware including custom ROMs and allows us to hack our phone. Therefore, having a custom Recovery on your Samsung Galaxy is essential to doing cool things after you’ve rooted your device.

Step 4: Restore from Nandroid backup

If something went wrong and your device isn’t working the way it should, you can restore from a Nandroid backup if you have previously created one. There are two ways to do this. If your phone still boots up, you can open ROM Manager and tap on Manage and Restore Backups. If your device does not boot up into the Android operating system anymore, you can boot into the Recovery mode instead and restore the Nandroid backup from there. We’ll be doing it that way here.

Action: Get into Recovery mode. Long press Home, Volume up, and Power at the same time. You might have to search online for a different combination for your device. In Recovery mode, select backup and restore, select restore, choose the backup from which you want to restore (the first one in the list is your most recent backup), select Yes – Restore, and confirm.

Once the restoring process is finished, your phone will boot up and you will have a fully working operating system again, ready to be hacked again.

Troubleshooting

Error: MD5 Mismatch

Solution: If you get the MD5 Mismatch error when you’re trying to restore from your Nandroid backup, don’t panic. I found a quick fix to get you up and running in minutes. Read this MD5 Mismatch Fix tutorial.