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Most of us would rather install an Android update over the air. But there are a few of us who are adventurous and would like to do the install their own way. With Android’s current version now being Nougat (available in some devices), those who would like to turn back the clock and install a slightly older version would have to resort to other ways.

Use a factory image

Using a factory image involves you flashing the Lollipop OS into your device. However, this comes with certain risks so do this only if you’re very sure or know what you’re doing.


The best thing for you to do before attempting to flush the OS into the device is to backup your device. This makes it easier to switch back in case you fail.

One of the biggest problems with doing this is getting the system.img error. Others include missing back buttons and the phone memory downgraded to 16 GB. However, most of the problems can be fixed by a complete system wipe.


But if you’re still intent on doing this, here are the steps to follow:

  1. Download and install the Lollipop SDK on your Windows computer. Two programs will be installed: ADB and Fastboot. These two will be accessible through the command terminal of your computer.
  2. Add the SDK folder to the PATH variable. To do this, right click on My Computer then click on Properties. Click on Advanced System Settings then Click on System Properties -> Advanced -> Environment Variables. Select Path then click on Edit. Type in the name of the directory where the SDK is located.
  3. Enable USB debugging on your device. To do this, go to Settings -> About Phone -> Software information. Tap Build number seven times. Go to Settings -> Developer Options. Tick USB Debugging.
  4. Download the factory image for your device. Extract the image on your computer.
  5. Connect your device to the computer using USB.
  6. Start the device in Fastboot mode. To do this, hold a key combination while you power up the device. You can also boot into Fastboot mode using the ADB tool.
  7. Open a command terminal. Navigate to the unzipped image file. Execute the file flash-all.bat which installs the necessary bootloader, baseband firmware and operating system.
  8. Lock the bootloader. This is for security purposes. To do this: oot the device in Fastboot mode while still connected via USB. Use the command line to execute fastboot oem lock.

While Android 7.0 Nougat will be available for Nexus 6, 5X and 6P, this guide comes in handy in case you want to switch to an older version.