The latest version of Android 4.2.2 Jelly Bean has been recently released by Google and the Nexus device lineup would be the first to feel a new experience. Many Android devices are still not up-to-date including those from the LG lineup such as LG Optimus G. In October 2012, LG made a press release about the Jelly Bean update for Optimus G supposedly available two months after the announcement.
Sprint LG Optimus G received an Android 4.1.2 update even if the roll-out date is not specified; several users have already gotten their hands on it. Sprint hasn't yet made any confirmation that they have pushed a release for the Jelly Bean update. Another speculation is that LG might be the actual source of the 474MB update. The firmware LS970ZVB is out, and for those tired of waiting to have the Jelly Bean taste, view the XDA forum for more details.
While Sprint and LG are busy for updates, Cyanogenmod 10.1 has offered the Android 4.2.1 Jelly Bean version to the Canadian LG Optimus G. Although the CM 10.1 arrived for Optimus G, the developed firmware by senior XDA developer Chadouming works for the TELUS version of the device. Other models are not yet ready for this CM, and flashing Nexus 4 ROM on the device might actually cause it to brick.
Warning: This guide must be follow strictly to avoid any possible damage to the device. Developers and sources will not be held responsible for anything that might go wrong with the device,
DO IT AT YOUR OWN RISK Preparation:
1. The LG Optimus G must be rooted, have already unlocked bootloader, and ClockworkMod recovery must be currently installed.
2. Back up everything from SMS to files. The procedure may need to wipe out all data inside the device.
3. Contacts can be backed up using Gmail account via syncing.
4. Create a backup copy of your SMS using apps such as Go SMS Pro, SMS backup & restore, or SMS backup+
5. For backing up any application you want to be restored after the flash, install any file manager with application backup feature. File Expert is an example of this app.
6. Download the necessary files here which are going to be used for flashing.
7. Don't forget to download Google Apps package.
1. Copy both the CyanogenMod ROM and the Google Apps package zip files to the internal storage of the device.
2. Switch off the device and reboot it to the "Recovery Mode." Press volume up and power button and choose recovery option from the bootloader.
3. Create a nandroid backup from the current ROM in the recovery mode. This is vital just in case something goes wrong which will revert the device back to its original state before the flashing. Select "Backup and Restore" and then selected "Backup" to create the nandroid backup.
4. Press "Go Back" to return to the main menu.
5. Select "Install zip from SD card" and then select "Choose zip from SD card". Find the downloaded ROM zip which you have transferred to the internal storage and install it.
6. Use the same method for installing the Google Apps zip package.
7. Wipe all data by selecting "Wipe data/factory reset" and confirm it.
8. Press "Go back" and select "Reboot system now" to reboot the device.
The boot might take several minutes which is normal for most newly flashed devices. Just in case it got stuck, turn off the device, remove the battery, and turn it on again. You can comment to the original XDA thread link for any errors experienced.