An over-the-air update for Android 5.0 Lollipop will begin arriving on Google's Nexus line of devices in the coming days. The company recently published factory images for the update for the Nexus 5, Wi-Fi-only Nexus 7 and the Nexus 10. These images can be loaded onto your Nexus device and restore it to a new, out of box state. It should be noted, however, that this will erase all of the data on your device.
The method outlined in this guide is for Windows computers only. There are other options available for Mac users, although you could always load a boot camp or a virtual Windows PC to perform this.
Nexus Root Toolkit
A developer that goes by the alias of WugFresh created a tool that can easily unlock the bootloader and root your Nexus device. I've been using the tool for quite sometime and it's incredibly straightforward. Please note that is may void your warranty, and that CNET is not responsible for anything that may happen to your device. You should proceed with caution, and non-experienced users may just be better off waiting a few days for the update.
With that said, download the tool from this website and install it on your Windows computer. Launch the program and select the device you are using and it's current build. To find the build on your Nexus device, enter Settings and scroll down to About phone. You will find the information you need under Build number.
While you are in the About Phone section, click on the Build Number option seven times to enable Developer mode. Then, in the Developer mode options, enable USB debugging. A screen will pop up on your phone when the program attempts to make a connection. Make sure to allow it.
If the program and computer aren't recognizing your device, you will have to install software drivers. In the Nexus Root Toolkit, click on the "Full Driver Installation Guide" button and follow steps one through four. This is the most difficult part of the process. Be sure to follow the steps exactly and make sure to restart your computer when prompted to do so.
Flashing the images
Before you can flash a factory image, you must first unlock your bootloader. Click the Unlock button in the Nexus Root Toolkit, click OK, followed by Yes. Your device will reboot a few times, but don't freak out. Let the program do its thing.
Once your device has successfully rebooted, skip the initial setup and go right into the settings menu. Once again, click the Build number option to enable Developer Mode and select USB debugging.
Now head to Google's developer website and download the 5.0 factory image. Be sure to download the image that corresponds with your device. I am using a Nexus 5, so I downloaded the "hammerhead" image.
In the Nexus Root Toolkit, click the "Flash Stock + Unroot" button, followed by the option to use an image you previously downloaded. Click OK, select the file from your computer, and copy and paste the MD5 checksum number found next to the file you downloaded on Google's website.
Once again, this will take some time, so be patient and let the program do its thing. Once your phone has rebooted, you will have a fresh new install of Android 5.0 Lollipop.
If the available internal storage displayed on your device is wrong. Head to Settings, select Backup & reset, click on Reset phone, followed by Erase everything. This should fix the problem.
For more Lollipop tips, please see CNET How To's guide to Android 5.0 Lollipop.