1 Install LG Support Tool v.1.6.7.1

2 Extract HardReset_LG_Flasher.7z

3 Copy LGMLauncher.exe and LGUserCSTool.exe to C:/ProgramData/LGMOBILEAX

4 Install drivers from HardReset_LG_Flasher LGUnitedMobileDriver_S50MAN310AP22_ML_WHQL_Ver_3.10.1_3.10.1.0(1).exe Disconnect phone before install and connect after install. It should appear in Device manager as composite LG device.

4 Run HardReset_LG_Flasher.exe

5 Load kdz file

6 Select Normal web upgrade test

7 Click on Clear phone Software update Registry

8 Select language and click on OK

9 Upgrade in progress

if you have non original rom maybe you have to extract kdz by KP500-Utils-EN.exe ( LG Utils 0.4.2) and 7Zip.
and flash by LGMDP v.1.5 Build 13.06
it only rewrite boot image not system so you have to ho whole procedure.
Full Arcitle about this part

Rom V20D_00.kdz Android 2.2 Foyo
Rom V10I V10F Android 1.5-1.6 probably