The current firmware of Nexus 5 is 5.0.1, but you can start upgrading your phone manually to the latest version Lollipop 5.1. The upgrades includes “on-body detection” and HD voice compatibility.
To start upgrading, you need to download the following:
1. Google USB Driver (http://developer.android.com/sdk/win-usb.html)
2. Android SDK Platform Tools (http://files.gensanblog.com/platform-tools.zip).
3. Android 5.1 Firmware for Nexus 5 (https://dl.google.com/dl/android/aosp/hammerhead-lmy47d-factory-6c1ad81e.tgz)
4. You need to have WinRar or 7-zip to open .tgz and .tar files.
After downloading the required files, we are now ready to start.
1. First, Install Google USB Driver
2. On your Nexus 5 Settings, enable the “Developer options” by going to Settings > About phone > and tap “Build number” 5 to 10 times.
3. Once done, go to Settings > Developer options and enable the “USB debugging”.
4. Let’s go back to your Computer. For us to have the same step, let’s create a folder in our Drive C:\ and named it as “nexusupdate”.
2. Unzip the “hammerhead-lmy47d-factory-6c1ad81e.tgz” to “C:\nexusupdate”.
3. After unzip, you will get a file called “hammerhead-lmy47d-factory-6c1ad81e”, rename the file to “hammerhead-lmy47d-factory-6c1ad81e.tar” and unzip it again in “C:\nexusupdate”. You will get a folder called “hammerhead-lmy47d”
4. Now unzip the “platform-tools.zip” to the directory “C:\nexusupdate\hammerhead-lmy47d”.
5. Next is we need to unzip the “image-hammerhead-lmy47d.zip” to “C:\nexusupdate\hammerhead-lmy47d”
5. Once done.. Open “Command Prompt (Admin)”
6. On CMD, type the following command
fastboot oem unlock
fastboot flash bootloader bootloader-hammerhead-hhz12f.img
fastboot flash recovery recovery.img
fastboot flash boot boot.img
fastboot flash system system.img
7. (Optional) If you want to reformat everything do the following:
fastboot flash cache cache.img
fastboot flash userdata userdata.img
8. Now we can reboot your phone