- Download and install LG Mobile Driver 4.1.1
- Download and install LG Flash Tool 2014 - KDZ Flash Software
- Download the official firmware for your LG Optimus 3D (LGP920).
- Place device in download mode. Power device off, while holding volume up, plug computer usb cable into your phone.
- Run the LG Flash tool .exe file
- Select "CDMA" as device type and "diag" as phone mode.
- Use the KDZ file you previously downloaded.
- Use" Normal Flash" to flash without losing any data. This is to fix system errors. Flashing anything besides the same current firmware will result in a boot loop.
- Use "CSE Flash" to wipe all data and flash stock firmware onto your device. Use this if you are soft bricked, boot looping, downgrading, sideloading update or just need to go back to 100% stock.
- Click start and choose your country and language in the pop up window.
- Hit ok and don't touch anything until it says 100%.
Notic: Please keep in mind that, you must work with LG flash tool at your own risk and also full responsible with you.