Flashing Instructions
To flash a device using one of the system images below (or one of your own), you need the latest fastboot tool. You can get it from one of the sources below.
From a compiled version of the the Android Open Source Project.
From the platform-tools/ directory in the Android SDK. Be sure that you have the latest version of the Android SDK Platform-tools from the SDK Manager.
Once you have the fastboot tool, add it to your PATH environment variable (the flash-all script below must be able to find it). Also be certain that you've set up USB access for your device, as described in the Using Hardware Devices guide.
Caution: Flashing a new system image deletes all user data. Be certain to first backup any personal data such as photos.
To flash a system image:
Download the appropriate system image for your device below, then unzip it to a safe directory.
Connect your device to your computer over USB.
Start the device in fastboot mode with one of the following methods:
Using the adb tool: With the device powered on, execute:
adb reboot bootloader
Using a key combo: Turn the device off, then turn it on and immediately hold down the relevant key combination for your device. For example, to put a Nexus 5 ("hammerhead") into fastboot mode, press and hold Volume Up + Volume Down + Power as the device begins booting up.
If necessary, unlock the device's bootloader by running:
fastboot oem unlock
The target device will show you a confirmation screen. (This erases all data on the target device.)
Open a terminal and navigate to the unzipped system image directory.
Execute the flash-all script. This script installs the necessary bootloader, baseband firmware(s), and operating system.
Once the script finishes, your device reboots. You should now lock the bootloader for security:
Start the device in fastboot mode again, as described above.
Execute:
fastboot oem lock
Locking bootloader will wipe the data on some devices. After locking the bootloader, if you want to flash the device again, you must run fastboot oem unlock again, which will wipe the data.
