The LG G3 AT&T variant has a new method for installing Team Win’s TWRP Recovery. The TWRP Recovery is main people’s favorite custom recovery because it’s quicker to use than ClockworkMod recovery. The menu’s found inside are also short, sweet and easy to understand. if you want to gain root access and flash a custom recovery image so you can begin installing custom ROMs on your smartphone, check after the drop on how to do that.
You should turn on the handset and head to the Settings, followed by the About Device menu and check the model number matches with D850. You cannot use the guide on a different model number.
BEFORE YOU BEGIN
- You are still voiding the warranty by following this guide using the Auto-Rec application. Flashing the stock version of Android once again after this should take away the root access and restore the warranty.
- Download and install the LG USB Drivers .
- You must enable the Unknown Sources option from the LG G3 by turning it on and navigating over to the Settings > Security and then enabling the Unknown Sources from the list.
- Enable the USB Debugging Mode: Settings > About Device > tap the build number seven times. Go back to the Settings > Developer Options > check the box for enabling the USB Debugging Mode.
HOW TO ROOT AT&T LG G3 D850 AND INSTALL TWRP RECOVERY
- Download the LG_One_Click_Root_v1.3.msi  to the desktop of the Windows PC.
- Extract the package and run the rooting tool on the computer. You need to double click over the LG Root Script.bat file to do that.
- Now just follow the set of on-screen instructions and you’re done.
- Now that you have root access it’s time to flash the TWRP Recovery.
- Unplug the G3 from the computer.
- Download the Auto rec app direct from Google Play here  directly to the smartphone.
- Once it’s finished downloading, tap on the new app icon available in the app drawer.
- Wait a few moments as it backs up your data automatically.
- Click the TWRP Recovery option when it’s available.