To root your AT&T LG G4 H810 device, we need to have it running on stock Lollipop ROM. There are no perfect root methods available for Marshmallow 6.0 yet for LG G4. Here is the step by step guide available to downgrade AT&T LG G4 from Marshmallow 6.0 to Lollipop 5.1 which further can be rooted easily running stock ROM.
There are few prerequisites before we start. We need to download necessary files to begin with.
1. LG UP. (Click to download)
2. LG Drivers. Install the DLL first and then install the drivers, DLL file wont give you any dialogue box and will install in background so don’t worry. (Click to download)
3. Zipped TOT file. (Click to download)
4. Backup all your data because phone will be wiped completely in this process.
Now lets begin with the steps to downgrade AT&T LG G4.
1. We need to make sure that USB debugging is enabled on our device. To do that, press “Build Number” under About phone>>Software for 7 times, it will enable Developer options on your phone. Navigate to Developer options in Settings and enable ‘USB Debugging’.
2. Lets connect our phone to the PC, make sure to let it install the drivers into PC from phone screen. Choose MTP as connection method when it prompts on the screen after connecting it to PC. Open LG UP while phone is still connected to PC.
3. Select TOT file we just downloaded in LG UP’s file path. To select it, press the 3 dots almost in the lower right of the software. Refer to the image below for convenience.
4. Exit LG UP software. Do not disconnect device from PC. Lets start LG UP again, you should see the TOT file already selected. Just select “Refurbish” and click on Start. See image below for reference.
5. Do NOT disconnect your phone before the process hasn’t finished. It should complete in about 10 to 15 minutes and phone should reboot normally.
Hurrah! You have successfully downgraded AT&T LG G4 from Marshmallow 6.0 to Lollipop 5.1 10o version. If you further want to root your device, please follow this step by step guide on how to root your LG G4.