How to Upgrade Your Nexus Device Without Waiting By Flashing a Factory Image
Unlock Your Device
Download the System ImageIf you want to do it the manual way, read our guide to Flashing your Nexus device with a new ROM and complete the process under “Unlocking the Bootloader with Android SDK.” You can stop after issuing the “fastboot oem unlock” command and verifying the device is unlocked by looking for the open lock icon during the boot process. There’s no need to install ClockworkMod Recovery — in fact, the below process will erase any custom recoveries you have installed. You can reinstall them later, if you like.
Decide Whether to Wipe Your Data
Get ADB and Fastboot
Flash the System Image
adb reboot bootloader