Android 5.1 Lollipop
Unofficial Android 5.1 Lollipop build now available for Nexus 4: How to installYouMobile

In less than 24 hours since Google's official announcement of the Android 5.1 Lollipop update, several Nexus devices including the Nexus 5, Nexus 7 2012 (Wi-Fi) and Nexus 10 have received the Android 5.1 factory images from the Android maker, while Nexus 4 has received an unofficial Android 5.1 Lollipop build that can be flashed via custom recovery.

Nexus 4 users who do not wish to wait for the official Lollipop factory images or OTA release from Google can install the unofficial build of the Android 5.1 Lollipop ROM on their handset, by following the step-by-step guide provided below.

IBTimes UK reminds readers that it will not be held liable for any damage to device during or after the unofficial Lollipop ROM installation. Users are advised to proceed at their own risk.

Pre-requisites

  • Verify that the correct USB drivers are installed on your LG Nexus 4 (download latest drivers here).
  • Back up important data and settings on your phone via custom recovery (CWM or TWRP).
  • Enable USB debugging mode on your Nexus 5 by navigating to Settings > Developer Options.
  • Ensure your phone's battery has at least 80% charge, before you proceed with the ROM installation.
  • Verify that your LG Nexus 5 is factory unlocked, bootloader unlocked and rooted.
  • The firmware and the instructions provided in this guide are meant for the LG Nexus 4 (aka mako) only. Do not attempt installing this firmware on any other variant as it may brick the device. Verify the device model number by going to Settings > About Phone.

Downloads Required

Unofficial Android 5.1 Lollipop build for Nexus 4

Google Apps

Steps to install the unofficial Android 5.1 Lollipop build via CWM recovery on Nexus 4

Step 1 - Download Android 5.1 Lollipop unofficial build for Nexus 4 on the computer.

Step 2 - Connect and mount the phone's USB mass storage on computer with USB cable.

Step 3 - Copy the downloaded Android 5.1 ROM zip file to the root folder on the phone's SD card.

Step 4 - Power off the phone and disconnect its USB cable from computer.

Step 5 - Boot the device into BootloaderMode by pressing and holding Volume Up, Volume Down and Power buttons together.

Step 6 - Follow the onscreen instructions and then choose Bootloader option. Then select Recovery from the Bootloader menu.

Step 7 - Once the phone enters into CWM Recovery, perform a full data wipe task by clicking Wipe Data/Factory Reset. Use the Volume keys to navigate between options and Power button to select an option in the Recovery Mode.

Step 8 - Then, perform Wipe Cache Partition and wait until the process completes.

Step 9 - Now perform Wipe Dalvik Cache as well. To do this, go to 'advanced' option and then click Wipe Dalvik Cache. This will help in preventing boot loop issues or any boot ROM related errors during firmware installation.

Step 10 - Return to the main recovery menu and choose Install Zip from SD card.

Step 11 - Now click Choose Zip from SD card. Use volume keys to navigate to the Android 5.1 ROM zip file that you copied earlier to your phone's SD card and choose it by tapping the Power button. Confirm the ROM installation on next screen and the installation process will begin.

Note: Repeat step 10 and step 11 to install Google Apps (Gapps) as well.

Step 12 - Once the ROM and Gapps installation completes, go to "+++++Go Back+++++" and select Reboot System Now in the Recovery menu.

The phone will now reboot and the first boot may take about five minutes to complete. So, please be patient.

Your Nexus 4 is now running the latest Android 5.1 update via unofficial Lollipop build. Go to Settings > About phone to verify the firmware version installed.

[Source: XDA]