LG Optimus 2X stuck in S/W Upgrade please wait while upgrading

** I Will Not responsible for any damage done with use of below mentioned methods. **

If you are not trying to apply the update from LG  and if your LG Optimus 2X or T-Mobile G2X is freezes after this message for long long time then follow below steps in order to recover the mobile. 
- Remove the battery. Wait for some time and put battery back again. Now start the mobile with power button. Do not hold any other button.
- Even this time as well if you see the same S/W upgrade message you will need to install the custom recovery tool on your mobile using NVFlash or OneClickRecoveryFlasher. Follow the link http://forum.xda-developers.com/showthread.php?t=1044326.
- Else you can use the SmartFlash Tool for LGP990 and recover the mobile with LG stock ROM. Follow the link  http://forum.xda-developers.com/showthread.php?t=1448803  for how to use SmartFlash tool.  
Note: You may loose your data by following above steps. 

Error: command failure: partition download failed

This post is for those who are trying to flash ClockworkMod using NVFlash or OneClickRecoveryFlasher or manually using command prompt on LG Optimus 2X or T-Mobile G2X. 

Carefully looking at the error you can recognize that error is about the partition failure, it means command failed to recognize/find the partition you have specified in the command.  If you are using OneClickRecoveryFlasher you may find the FlashCWMRecoveryXXXX.cmd file which will contain the commands that I am talking about.

The partition number is mentioned after the --download flag. As marked in red in below command :

nvflash.exe --bct E1108_Hynix_512MB_H8TBR00U0MLR-0DM_300MHz_final_emmc_x8.bct --bl fastboot.bin --download 5 recovery-clockwork-5.0.2.0-p999.img

In order to resolver the error the partition number must be correct. 

In case if your trying to flash the recovery in T-Mobile G2X use partition number as 5. 

In case if your trying to flash the recovery in  LG Optimus 2X use partition number as 14. 

How to install Custom ICS (Android 4.0) ROM on LG Optimus 2x (P990)

I WILL NOT BE HELD RESPONSIBLE FOR ANY DAMAGE CAUSED BEFORE, DURING, AND/OR AFTER INSTALLING CUSTOM ROM. PLEASE READ EVERYTHING, MAKE BACKUPS, AND FLASH AT YOUR OWN RISK.
 
With the help of ROM Manager application you can easily upgrade your LG Optimus 2X (LGP 990) with ICS 4.0.4 custom ROM. 
For this you will have to first ROOT your device. To know how to root your LG Optimus 2X click here. Then install a free ROM Manager application available in Googly Play market. 
Now download the custom ROM that you want to install/apply. Copy the custom ROM to your internal memory of LG Optimus 2X (LGP 990), you can even copy the ROM to external SD card as well.  Now follow below mentioned steps to apply the custom ROM.


1. Launch the ROM Manager application, you will see the UI as below:

2. Click OK. Firstly you should backup your current ROM. You can have backup in two forms with Data and only ROM. You should take backup in both the form so that you can at least return to old ROM if something goes wrong. 

3. Once you have backup of your current ROM. Now launch the ROM Manager again. Now select install ROM from SD card option. 

4.Before you install new ROM you should wipe the cache and data partition depending upon compatibility with your current partition. Ideally flashing data and cache partition is good option.

Now selected ROM will get updated.

Some of the custom ROM's can be downloaded from below links :

http://forum.xda-developers.com/showthread.php?t=1735785

http://forum.xda-developers.com/showthread.php?t=1508492