There are a number of tools that you can use to root, unlock the bootloader, backup, or update the firmware of a Nexus phone or tablet. But the Nexus Root Toolkit from WugFresh is probably one of the easiest of those tools… and now you can use it to install or root Android 5.0 Lollipop.
Nexus Root Toolkit version 1.9.4 was the first to add full support for Lollipop, but any version with a higher number should work as well.
You can use the toolkit to download and install the latest factory image to your Nexus 4, 5, 7 or 10 tablet and once you’ve loaded the operating system the toolkit can also walk you through the process of rooting your device and/or installing a custom recovery such as TWRP.
Before you get started, you can also use the toolkit to help you install adb drivers and backup your device, among other things.
It’s usually a good idea to have some familiarity with Android adb commands before using a toolkit like this, because if anything goes wrong you may find the automated toolkit can’t help you. But if you don’t feel like entering a bunch of commands by hand, it’s nice to have an app that’ll let you do everything with just a few clicks.
Note that the Nexus Root Toolkit doesn’t currently support the Nexus 6, Nexus 9 or Nexus Player yet, but it does work with every other member of the Nexus family starting with the Nexus S.