Google releases latest versions of Android on the Nexus devices first and provides the factory images for the updates directly on the Google’s developer site. Sometimes the OTA updates scheduled for your device might get stumbled in the way and you might get extremely curious on getting the latest version of Android on your Nexus device or you just want to revert back to stock from the custom roms, in these cases you need to know how to flash the factory images manually.
Actually the process is quite simple and you can do it in a matter of minutes if you have all the required files with you. All you need for flashing the factory image to your device are the ADB/Fastboot files and the factory image destined for your device model. Please be careful on choosing the factory images, always download the images by checking the model numbers and code names to avoid bricking your device.
  Downloads
Download the ADB+Fastboot files and the relevant factory image from the download links provided below.
ADB+Fastboot file → download link.
Factory Images → download link.
Step By Step Procedure:
- Download the necessary files for your device and once again cross verify them.
- Extract the ADB+Fastboot files to a folder on your computer (avoid extracting to your desktop, there might be problem when you have a user name which has space in between like xxx yyy ) and install the USB drivers in case you are on Windows PC.
- Extract the Factory image you downloaded to the same folder, the factory image will give you a file containing the codename of your device,  two files with the name flash-all but with different extensions, and a bootloader image file.
- Make sure all the extracted contents of the factory image are in the same folder as the ADB and Fastboot files, otherwise you will get a file not found error.
- Connect your device to your PC and make sure the device shows up in device manager.
- Now click on the flash-all.bat if you’re on Windows PC or flash-all.sh if you’re on Linux, now the flashing starts.
- Wait until the flashing is completed and then simply reboot your device.
That’s it you can flash any factory image file from the Google’s page to revert back to stock or upgrade to latest builds following this simple guide.
