Before we get started updating your Optimus One Froyo to Gingerbread please read the following details carefully.

1. This update is exclusively for LG Optimus One P500
2. This will not work with locked phones like T-Mobile, AT&T and CDMA Optimus One Phones.
3. This Gingerbread update is not 100% stable, there might be bugs but we are sure that developers will fix them.
4. This is an official release but we will teach you how to install it manually with your PC.
5. Back up your phone date but not necessary. I suggest this Android App if you wanted to save your phone’s SMS. SMS Backup and Restore Here.
6. Reset your phone. Hold Home and Volume Down and press Power button until it turns on.
7. Update at your own risk, we are not responsible to what might happen with your phone.

Requirements:

1. Gingerbread 2.3.3 firmware. Here Mirror
2. Firmware Updating Software. Here.
3. LG United Mobile Driver. Here.
3. PC and at least 80% charged phone.
4. USB cable for your Optimus One.

How to Install Android 2.3.3 Gingerbread on LG Optimus One

1. Extract “KDZ FW UPD EN.zip” and “LGUnitedMobileDriver.rar”
2. Run LGUnitedMobileDriver and “msxml” updater
3. Set your phone on USB Debugging mode. Go to Menu – Settings – Applications – Development and check USB Debugging
4. Connect your LG Optimus One to PC but don’t turn on USB Storage
5. Run “KDZ_FW_UPD”
6. In the software update select Type “3GQCT” and select PhoneMode “DIAG”
7. Select “V20E_00.kdz” file in the field of KDZ file
8. Press Launch software update.
9. Your phone will be on “Emergency Mode” while it updates
10. Wait until the updater said FINISH and your done.

When it is done, disconnect your phone from PC and Switch it On and you will see that Gingerbread is running on your phone.

I hope this helps you.

[source:androidflip.com]