Android 5.1.1 Lollipop OTA Update, Factory Images For Nexus 10, Nexus 7 Available: Nexus 9 To Get It Soon [How to Install]
Android 5.1.1 Lollipop Update For Nexus 10, Nexus 7: Factory Images, OTA Update AvailableScreenshot from Google's Android Official Site

Nexus 5 owners were left disappointed after Google pulled back Android 5.0 Lollipop OTA (Over-The-Air) update owing to bug issues after announcing its roll-out to the device on 3 November. But the wait is finally over now that the software is up for installation.

Google made Android 5.0 Lollipop OTA update to the Nexus 4, Nexus 5, Nexus 7 (2012 & 2013 editions), Nexus 10, and Google Play Edition devices, including Sony Xperia Z Ultra, Samsung Galaxy S4, HTC One M7, M8, LG G Pad 8.3, and Moto G on Thursday after weeks of anticipation.

Meanwhile, the Nexus 4 owners, along with Nexus 7 (2013) and Nexus 7 (Mobile), is yet to get factory image of the new software, though it should be made available soon.

The fact is it will take some days, even weeks in some countries to get Android 5.0 Lollipop update as Google is expected to roll it out in phases. To check if the firmware update is available for your device, go to Settings-->About--> Phone Software updates-->Check now. You may also get a notification if the firmware update is available for your device.

The Nexus 5 and other Google Play Edition device owners, who have received the Android 5.0 Lollipop update, need to follow certain procedures before manually installing the software.

- Make sure that your personal data like photos and other files are backed up before starting the update, as all user data will be erased during installation.
- Connect Nexus 5 handset to your computer using a USB cable.
- Install Android SDK on your machine with ADB and Fastboot command successfully working. [Tutorial for installing Android SDK]
- Download 7zip or a similar program that can handle .tgz and .tar files and save it in your computer.
- Make sure that you get the right factory image for your device and it can be downloaded on Google Developers page.

How to manually update Android 5.0 Lollipop on your Nexus 5:

- Boot your Nexus 5 device into fastboot mode by turning it off and holding down the volume up before pressing power.
- Use 7zip from your computer to extract the .tgz file. Use 7zip again to extract the .tar file from the .tgz. file.
- Copy all the extracted files and paste them on platform-tools folder in the Android SDK on your computer, which should be in C drive, and under Program Files (x86) on Windows.
- Connect your device to your PC. ADB and Fastboot commands should be working by this time.
- There are two flash-all files - double click "Windows Batch File" if you are on Windows, and file if you are on Linux.
- Installation should start by now with a box popping up if you have correctly followed all the procedures.
- Do not unplug your device while installation is in progress.
- Your Nexus device will reboot automatically after installation is done, and Android 5.0 Lollipop boot animation will start up.
- You can disconnect your Nexus device from your computer. Now, you have Android 5.0 Lollipop.