Restoring Your Nexus or Pixel: A Deep Dive into Factory Images

If you've ever ventured into the world of custom ROMs, rooting, or other advanced modifications on your Nexus or Pixel device, you might find yourself in a situation where you need to revert back to the original factory firmware. That's where factory images come in handy. This guide will walk you through everything you need to know about factory images, including when to use them, how to use them, and important precautions to take.

What are Factory Images?

Factory images are essentially complete snapshots of the software that comes pre-installed on your Nexus or Pixel device. They contain all the necessary files to completely restore your phone or tablet to its original state, as if you just took it out of the box. You can download the latest images for your devices from Google here.

Why Use a Factory Image?

Factory images are most useful in these scenarios:

• Reverting from Custom ROMs: If you've installed a custom ROM and want to go back to the official Android version.
• Unbricking Your Device: If your device is stuck in a bootloop or experiencing other software issues that prevent it from starting up properly.
• Starting Fresh: If you want to wipe your device completely clean and start with a fresh installation of the operating system.

Factory Image vs. OTA (Over-the-Air) Updates

While both factory images and OTA updates can update your device's software, they serve different purposes and have different implications:

• OTA Updates: Incremental updates that are delivered wirelessly. They typically don't erase your data and are the recommended way to keep your device up to date under normal circumstances. Learn more about full OTA images here.
• Factory Images: Complete system images that overwrite everything on your device. They erase all user data and require unlocking the bootloader (which can make your device less secure).

Typically, using a full OTA image is easier and safer. It doesn't require a data wipe or bootloader unlocking. However, if you're dealing with significant software issues or reverting from a custom ROM, a factory image might be necessary.

Important Considerations Before Flashing a Factory Image

• Data Loss: Installing a factory image will erase all data on your device. Make sure to back up any important photos, videos, documents, and other files to your Google Account or another secure location. Google provides documentation on backing up your data to your Google Account here.
• Bootloader Unlocking: Flashing a factory image typically requires unlocking the bootloader. Unlocking the bootloader can make your device less secure, as it removes certain security restrictions.
• Terms and Conditions: Downloading and using factory images is subject to Google's Terms of Service and Privacy Policy.

Special Instructions for Pixel 6, 6 Pro, and 6a Users Updating to Android 13

If you're updating your Pixel 6, Pixel 6 Pro, or Pixel 6a to Android 13 for the first time, it's crucial to follow these steps to avoid potential boot issues:

The Android 13 update includes a bootloader update that increments the anti-rollback version. This means you won't be able to revert to older Android 12 builds after flashing Android 13.

To prevent boot issues, flash the bootloader partition to the inactive slot after successfully updating and booting into Android 13 at least once.

You can do this in two ways:

Option 1 (Recommended): Sideload the full OTA image corresponding to your Android 13 build and reboot the device.

Option 2 (Using Factory Images):

1. Extract the contents of the factory ROM .zip file.
2. Identify the bootloader image in the extracted files.
3. Start your device in fastboot mode:
   • Using the adb tool: adb reboot bootloader
   • Using a key combo: Power off, then power on and hold the relevant key combination for your device
4. Flash the Android 13 bootloader to the inactive slot using the following command, substituting the correct bootloader image name:

fastboot --slot=other flash bootloader bootloader-raven-slider-1.2-8739948.img

5. Reboot to that slot to ensure the bootloader is marked as bootable:

fastboot set_active other
fastboot reboot bootloader
fastboot set_active other
fastboot reboot bootloader

6. Reboot into the current OS: fastboot reboot

Step-by-Step Guide to Flashing a Factory Image

Warning: These instructions are for advanced users. Proceed with caution, as incorrect steps can potentially damage your device.

1. Download the Correct Factory Image: Go to the Factory Images for Nexus and Pixel Devices page and download the factory image that corresponds to your specific device model and build number.
2. Install ADB and Fastboot: You'll need the Android Debug Bridge (ADB) and Fastboot tools installed on your computer. These tools allow you to communicate with your device in bootloader mode. You can download the Android SDK Platform Tools from the Android Developers website.
3. Unlock the Bootloader: If your bootloader is not already unlocked, you'll need to unlock it. This process varies slightly depending on your device. Generally, you'll need to enable USB debugging in Developer Options, connect your device to your computer, and use the fastboot flashing unlock command.
4. Flash the Factory Image:
   • Extract the contents of the factory image .zip file to a folder on your computer.
   • Open a command prompt or terminal window and navigate to the folder where you extracted the files.
   • Put your device in fastboot mode (as described earlier).
   • Run the flash-all script (or the appropriate command for your device). This script will flash all the necessary partitions to your device.
5. Relock the Bootloader (Optional but Recommended): Once the flashing process is complete, you can relock the bootloader using the fastboot flashing lock command. This will improve the security of your device, but it will also prevent you from flashing custom ROMs or making other modifications in the future without unlocking it again.

Staying Informed

The Android Developers Blog is a great source of information. Check it out here.

Conclusion

Factory images are a powerful tool for restoring your Nexus or Pixel device to its original state. However, they should be used with caution, as they erase all data and require unlocking the bootloader. If you're comfortable with the risks and understand the process, factory images can be a lifesaver when dealing with software issues or reverting from custom ROMs. Always remember to back up your data and follow the instructions carefully to avoid damaging your device.