Factory Image Flash a Nexus 5 Android Phone

I needed to re-image a Google Nexus 5 Android GSM smartphone with its stock factory image. Because I haven’t done this in a long while, I thought I would document what I did.

The instructions below should also work for the Google Pixel phone. I did the re-image using my Windows 10 desktop, but you can also do it on a Mac.

Note: Please backup your data because a factory image flash will destroy everything!

Install ADB and Fastboot

We need to install the software tools necessary to flash an Android phone. These are the Android Debug Bridge (adb), used to communicate with an Android device, and fastboot, used for writing directly to a device’s flash memory.

Thankfully, Google has separated these tools from the Android SDK into a smaller “SDK Platform Tools” package.

1. Download the SDK Platform Tools package; I downloaded “platform-tools-latest-windows.zip”.
2. Unzip to a directory, say “C:\Program Files\platform-tools”.
3. Add that directory to the %PATH% environment variable.
4. Launch a Command Prompt window and run “adb version”. I got “Android Debug Bridge version 1.0.39” as the response.

Enable USB Debugging

Enable USB debugging so adb can talk to the phone:

1. On the phone, go to Settings, “About phone”, and scroll to the bottom until you see “Build number”.
2. Click on the “Build number” seven times. You’ll see popups telling you how many times more to press to enable “Developer options”. (Ex: “You are now 3 steps away from being a developer.”)
3. Once done (you’ll see a “You are now a developer!” popup message), go back to Settings and you will see a new menu “Developer options”. Click to go into it.
4. Near the top, you will see an option “USB debugging”. Enable it.
5. Plug the phone into the computer and answer “OK” when prompted with “Allow USB debugging?”. (Windows 10 was able to automatically find and install the Nexus 5 driver. If your operating system fails to do so, you may need to find and install the driver for your phone manually.)
6. Open a Command Prompt window and run “adb devices”. It should list one device.

Note: You can see the status of and control how the USB connection behaves. On the connected phone, drag from the top, and you will see a message relating to the USB connection. If USB debugging is enabled, you will see the “USB debugging connected, Touch to disable USB debugging” message. If you disable USB, you will see a new “USB for charging, Touch for more options” message. You can change USB options to “File transfers” if you wish to browse files (such as pictures) located on the phone.

Find Factory Image

The hardest part of this process was finding the correct factory image to download for the Nexus 5. There were so many listed without any helpful instructions as to which image to download.

Here’s what I did:

1. Locate Google’s Factory Images for Nexus and Pixel Devices page.
2. Find the factory images for the “Nexus 5”, which is code-named “hammerhead”. (The “Nexus 5X” has code-name “bullhead”.)
3. Locate the last image, which is the latest and greatest version, “6.0.1 (M4B30Z, Dec 2016)”. (“M4B30Z” and similar are build labels, not model numbers, as I originally thought. So any of them should work with the Nexus 5, though an older Nexus 5 image would prompt you to update the latest.)
4. Unzip the downloaded “hammerhead-m4b30z-factory-625c027b.zip” file to any location; I just left the unzipped “hammerhead-m4b30z” folder in the Downloads folder.

Flash Factory Image

This is the easiest step because Google has provided a script with the factory image that does all the work.

1. Open a Command Prompt window and change directory to the unzipped factory image folder.
2. Run the “flash-all.bat” script. It only took 125 seconds to complete, ending with the message “finished. total time: 125.757s”.

The Nexus 5 then rebooted.

Note: It is recommended to do a data reset after a factory image flash. To do so, go to Settings on the phone, “Backup & reset”, and “Factory data reset”.

Need To Know

For your reading pleasure, below is the output of the “flash-all.bat” script:

For more details, I found this page, How to flash a factory image | Return to stock | Unroot your Nexus 5, very helpful.