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: (ZC: 这里的意思是,下面两个方法,2选1,我当时傻傻的以为需要两个步骤都要做...其实我第一个步骤已经成功就OK了)
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.