you can flash or downgrade or upgrade any LG device with kdz file by using this tool (LG flash tool 2014)
Requirements for Flashing .kdz on LG
2. Download LG Flash Tool 2014.zip and install it on your PC
3. you can Search and download all your desire kdz rom files for your lg device on google
Steps to Flash kdz on all LG phone
1. Open Lg flash tool.exe on PC, and Turn off your Phone then enter into download mode. every device has different method of entering into download mode, mostly you can enter into download mode by “press and hold the Volume Up +Volume Down and insert (plug in the) USB cable to your device.” OR “press and hold the Volume Up and insert (plug in the) USB cable to your device.” Wait until the Download Mode appeared on phone.
see picture belowe
2. Now on PC select KDZ file to flash and select normal flash or CSE Flash.(See picture) leave other options untouch
Normal Flash: Flash ROM without losing any data. Only use this when you need to fix system error. Beware of boot loop when flashing ROM that differ from current ROM on your phone or MOD ROM.
CSE Flash: Choose this option when you need a fresh format. All data will be lose. It’s suitable for upgrading or downgrading firmware, using this when you need to back to Stock rom.
Note:before do this u need to disconnect internet first
3. Select start on next screen
4. Select clear phone registry and ok on next screen leave options untouch
5. Now on next screen software upgrade will be started wait until it
reaches 100 %. After flash Phone may take some time to Boot so be
patient.
