I take no credit for this. All credit goes to the people whose link I used in this post. I am just putting things together.
Please read many times, understand, ask questions and then do it when you have all the info.
Here are detail instructions for downgrading LG Optimus M from 2.2.2 to 2.2.1
This Guide also works if one wants to set phone back to MetroPCS LG Optimus Stock ROM.
First install 7Zip tool on your PC.
Then install LG Mobile Support Tool.
I used the following link to get LG Mobile USB Drivers:
Download LG Mobile Support Tool to PC
Click on Download button and follow the install steps.
Turn off you phone and turn on. Then connect to USB port of PC using USB cable. Launch the LG Mobile Support Tool. First Install the drivers using LG Mobile Support Tool. Do not use Upgrade Software button.
I used the following thread to download LGNPST software on my Windows 7 PC
I extracted all files from the downloaded 7Zip file to C:\LGNPSTSW folder using 7Zip tool.
Then, I used the following instructions to install the LGNPST tool.
These instructions are from link:
Go to folder C:\LGNPSTSW
Run LGNPST_General_v1.2_Lab_Version.msi file, let it install if ask for reboot do it.
Then run LGNPST_Components_Ver_5_0_12_0.msi and let it install if ask for reboot do it.
Then run LGNPST _Generic_Models_ver_5_0_10_0.msi let it install if ask for reboot do it.
After all these files install, locate the LGNPST.exe file on your C:\LGNPSTSW folder and copy it to: C:\LG Electronics\LGNPST folder. Make a shortcut to the desktop because it`s required to run the program. Also copy the Model folder in your C:\LGNPSTSW folder to C:\LG Electronics\LGNPST as well.
Go to C:\LG Electronics\LGNPST\Model\MTP folder and keep only MS690.dll, MS690ZV3_36.scr, Reggie.exe and Setup.exe files. Delete other files.
**Then drag the MS690.dll file on top of the Reggie.exe file to register the MS690.dll file.** <---- Very Important step, Make sure to have Administrator Rights.
Download 3024 prl file from the below link:
MetroPCS New prl
Save prl file on your desktop.
Download OPTIMUS M STOCK ROM.7z file from:
OPTIMUS M STOCK ROM.7z
Extract MS690ZV4.bin file from the above zip file using 7Zip tool. Save it on your desktop.
Disconnect phone from USB, shut down and turn it on.
Connect phone to PC using USB cable.
Run LGNPST from your desktop shortcut. Make sure the program is set to Provision option and under Provision should be Upgrade. Where it says bin File click on the folder and look for MS690ZV4.bin that should be on your desktop and select it. Check the box where says SCR file and select the MS690ZV3_36.scr from C:\LG Electronics\LGNPST\Model\MTP folder. Check the PRL File box and select the 3024.prl from your desktop.
After that is done click start, the program needs the SPC code. So open cdaworkshop on your C:\LGNPSTSW folder and open cdma workshop.exe. After the programs load select your COM port where the cellphone is connected (It is shown on the right side of LGNPST on the phone info tab) then click connect. Go to the security tab and where it says SPC scroll down and select the LG method. Click read and write down the your SPC code, then type it in LGNPST and the process of updating your phone should begin. When the process is at 43% the cell phone restart DON`T do anything to your phone (don`t even touch it until it reaches 100%). After it reaches 100% the phone should be on the lock screen without service.
If you want to see the screen shots for running LGNPST tool the use the following link:
Now you can use Gingerbreak App to root your phone again.
[App] [26.04.2011][v1.2] GingerBreak APK (root for GingerBread) - xda-developers