[T-Mobile LG G2x] r4d14n7:
Yes, this guide is outdated a bit. I lost my job and in between school, 3 kids, and writing resumes, I do not have the time to do the proper research and update this. I apologize for my desertion, however, if anyone would like to take it over, feel free to copy/paste the contents of this post and repost, update, and request a sticky from the mods.

Disclaimer

If you have an LG P999 (Not the P990!) you should not brick while using this guide. If you do happen to brick your device, I will not accept responsibility for it. Nor will I support you. There is more than enough information in our section to fully troubleshoot almost any known problem. If I link to a thread, please read AT LEAST the original post (OP) in its entirety before taking the steps it contains. If a method I linked does not work, please let me know. I don’t have the time to read every post on every thread on every section.

This guide is for Windows users only. If you are on a Mac or Linux box, there may be ways of doing this, but I don’t have any way of testing it. You’re on your own.

Purpose

So you just got the LG P999 (T-Mobile G2x or Wind O2x) or you’ve had it for a while and finally decided to root it. This is an updated step-by-step guide on what you need to do in order to unleash your device.

Credit

Thank you to all of the developers and scripters out there. I didn’t do any of the work and I claim no rights to anything linked in this guide.

Thanks to:

KiNG OMaR

jboxer

Volk

kairi_zeroblade

Mr Rusty

phburks

All the other people who contributed to all of these methods.

Anyone who spends their free time coding, modding, troubleshooting, helping, and a special thanks to anyone who does his or her research.

General Information

This guide assumes you’ve had your phone long enough to have gotten T-Mobile’s 2.3.3 Gingerbread update by now. If you’re on 2.2.2 Froyo, search on how to update to 2.3.3 Gingerbread as it will upgrade (maybe?) your radio as well.

If you are an advanced user and coming from a different phone and are used to different practices, let me break it down for you. The bootloader and radio are already unlocked (or S-OFF, if you will). There are only 2 radios which may actually be exactly the same, but they are not flashable zips. All ROMs are compatible with either radio.

All links are tested and up-to-date as of 11 April 2012.

Step 1: CWM

Install ClockworkMod Recovery (CWM) via NVFlash. This should always be your first step no matter what you intend to do with your device. Installing CWM will allow you to flash roms, kernels, etc., as well as recover from minor bricks or bad flashes. DO NOT install CWM via Rom Manager. The following thread will help you install NVidia's APX drivers and flash CWM via NVFlash:

[RECOVERY]CWM-Based Recovery 5.0.2.8 For P999(Internal & External SD)

After completing this step, you will be able to access CWM at any time from a power off state by holding the Power and Volume Down buttons until the white “LG” logo goes away and the blue “LG” logo appears. Release the buttons when you see the blue "LG" logo and wait for the CWM menu to pop up. I recommend at this point that you test it out to make sure it works and that you perform a backup with CWM. Once backed up, copy it to your computer, burn it to a CD, archive it on your tape drive, whatever. It’s just good practice to keep these things in case someone’s link goes down and you really needed that file to return to stock.

Step 2: Decision

Here, you will make a decision:

Are there any apps that you need to save your progress in (for example, Angry Birds scores, etc.) and can’t simply be reinstalled?

If no, skip to Step 4: Flash

If yes, proceed with Step 3: Root

Step 3: Root & Backup

I know, I know. There are apps that can backup your angry birds scores and all that, but this makes reinstalling all of your apps easier. First, you need to download an app to backup your apps. Titanium Backup is my favorite. The price tag seems a little high at first glance, but it’s worth it, especially if you plan on doing this to other phones in the future. Download Titanium Backup from the market, and purchase the PRO key. If you want to go the cheap route, there are alternatives. Next, we need root access. Achieve this by following this post:

[ROOT] G2X Gingerbread 2.3.3. stock ROM with flashable zip in Clockworkmod Recovery

You have a rooted phone and Titanium Backup now. Open Titanium Backup and allow it root access. Press menu, then “batch” and backup user apps only. Never backup system data. You will only get yelled at when people find out that you backup system data.

Step 4: Wipe & Flash

Select a ROM. There are many to choose from (stock Gingerbread, AOSP-based Gingerbread, AOSP-based Ice Cream Sandwich, MIUI). If you’re not sure what you’re looking at, flash one from each category and play with it for 30 minutes to make a final decision. Please read the OP for the ROM you are flashing and follow their directions. If it is not based on the stock ROM, you will need to flash a zip that contains Google’s Apps (gapps). Read your ROM’s OP for the details on this.

When you flash a new ROM, at a minimum, perform the “Wipe Data/Factory Reset” in CWM just prior to flashing the ROM. This will clear old data and cache. I recommend using:

[TOOL] G2x Nullifier [UPDATED!] 26 March Cache only Nullifier!

The dual wipe nullifier is in my opinion, not needed. Single wipe will be fine. Keep in mind, once you nullify, you need to flash a ROM immediately after you nullify! If you reboot after nullifying, you have a soft-brick that should be recoverable, but that’s extra grief you don’t need. So, again, make sure you have a ROM ready to flash on your SD card BEFORE you use the Nullifier.

Step 5: Restore & Enjoy

If you backed up your apps in Step 3: Root & Backup, open up the Market and redownload Titanium Backup and the PRO key (or whatever cheap alternative you decide on) and start it up, granting root access. Press menu, “batch” and restore missing apps with data.

All done! If you want to underclock or overclock or flash kernels, you need to read up on it. They will not be included in this guide.

I am open to *constructive* feedback. If your feedback is “this guide sucks,” move on. I don’t need you here. If you have a legitimate problem with the contents and maybe a suggestion on how to fix it, by all means, let me know. I know there are a couple guides out there, but some are outdated. Just putting a fresh one up for those just joining the game.

I don’t ask for donations. Save them for the people who do the real work. If I helped you out, just hit the thanks button.