[LG Optimus 4X HD] skydev:
↓ A new root method! ↓

There is now a new root method, that does not require downgrade!

http://xdaforums.com/showthread.php?t=2180688

↑ Read this thread first! ↑

Prerequisites

A rooted LG O4X HD with a v10 firmware. (SuperSU preferred - personally tested)

Device adb drivers installed (so that a phone is detected as an ADB device when in B&R Recovery mode), adb itself is included in the archive

You need an installed Busybox! (/system/bin preferred, or need to edit bat file)

Warning: Do NOT do factory reset between step 1 and step 3! Otherwise /data/rootkit will be deleted, and you will have to start over.

Important note for linux users: bat files are for Windows. If you are using linux, i assume that it will be easy for you to open bat files and do commands by hand.

Step 0

Backup all your settings, and data from internal storage (!), cause factory reset (wipe) will be required.

You can try using LG's backup tool or Titanium Backup or anything else.

Also I'd strongly recommend removing SIM card and SD card from the phone.

Step 1

Make sure USB debugging is enabled (Settings -> Dev Options -> Debugging)

Connect your phone to your PC.

Execute file step0.bat and ensure that you grant su priv to ADB shell (2000).

Now execute file step1.bat - it:

- creates folder /data/rootkit

- copies busybox from /system/bin to /data/rootkit

- copies su from /system/xbin to /data/rootkit

- copies Superuser.apk from /system/app to /data/rootkit

- ensures owner and group of 0 for those files

- chmods files to required attributes (06755 for su, 0644 for apk, 0777 for busybox)

Result should be something like this: Note: In v2 i modified step1, so it tries to copy busybusybox from bin and xbin - one of them will fail, thats normal.

Step 2

Upgrade your firmware to v20a. For example: http://xdaforums.com/showthread.php?t=2069723

DO NOT DO FACTORY RESET! OR YOU WILL DELETE /data/rootkit FOLDER! DO STEP 3 FIRST!

Step 3

After successful upgrade shut down your phone.

Now, with USB connected (!!), hold volume up and power, and keep holding it at least until you hear windows "new device" sound.

You must see something like this:

Now execute file step3.bat - it:

- remounts system as writeable

- copies su to /system/xbin/

- copies superuser to /system/app/

- sets permissions on those files

Step 4

Now you can hold power button to reboot or just run step4.bat to reboot instantly.

Make sure that root is working, before doing factory reset!

Now you are STRONGLY recommended to do factory reset - or many things will mess up, such as lock screen settings or storage.

AGAIN warning, that factory reset WILL wipe internal storage, look at step 0

If you did all things correct, root will be kept (because it is on ro system partition now)

Step 5

Enjoy.

Note

If you are already at v20a and you want root, you can:

1) Wait for official release, with really unlocked BL - then it will be possible to install CWM -> get root

2) Wait until I make some interaction with B&R daemon in recovery

3) Wait for someone to find easier method

4) If you dont want to wait, you can go back to v10x (warning: all data will be wiped!), root phone, and do the procedure.

Any comments, notes, criticism or anything else very welcome!

Edit: In version 2 it tries to copy busybox from /system/bin and /system/xbin, thanks to AlderCass for pointing out