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.
If necessary, unlock the device's bootloader by running:
fastboot flashing unlock
or, for older devices, 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 flashing lock
or, for older devices, running:
fastboot oem lock
