** 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.