This is a guide on how to manually upgrade the LG Optimus 4X HD P880 to Android 4.1.2 Jelly Bean beta released or leaked firmware V20a. LG has not yet rolling out the official 4.1.2 Jelly bean for Optimus 4X, and this leaked JB 4.1.2 build will at-least probed that LG has continuing onto testing updates for Optimus 4X, this might also includes the L9 and L7. So, for now here comes the leaked version for those advance users who wants to give it try to update their LG Optimus 4X HD P880 devices to 4.1.2 JB in no time.
In Addition,you can now unlock the bootloader and easily install root on this v20a 4.1.2 JB version, then install a CWM recovery as you wish.
UPDATE: It is now Officially Rolling Out! All official V20A Android 4.1.2 Jelly Bean firmwares are now available to download.
How to manually install v20a 4.1.2 JB on LG Optimus 4X HD P880
This procedure is for advance users only. Remember, this is a leaked version or beta build release only, installing a leaked firmware onto your device might voids its warranty.
Disclaimer: Use of this guide is solely at your own risk. We shall not be held responsible if anything happens to your devices by using this guide.
Back up all important files stored from your device, although this process will not wipe data but if you need to factory reset, you should do some back-up first. Install necessary drivers from here. Grab the *.kdz file from XDA.
Turn off your phone,
Press and hold Volume down button and connect the phone to the PC while still holding Volume down button
Once the phone connected, you should see a S/W screen mode, if not re-install the necessary drivers
Now re-insert the battery.
Go to device manager and select “disable LGE Modem”.
Run the KDZ_FW_UPD.exe and Windows Enabler.exe as an Administrator.
Windows Enabler.exe should appear in taskbar somewhere near clock, click once till you can see ‘On’
In KDZ_FW_UPD.exe select 3GQTC as type and DIAG as PhoneMode
Browse and select your *.kdz file and press ‘Launch software update’
Do not click program window even if is ‘Not responding’! Wait till flashing ends
Phone will reboot and you can remove USB cable
How to Root, Unlocked Booloader, CWM Recovery
That’s all! Just let us know how all things work out.