I have a new tutorial and this for LG G2 or LG D802. Just keep on trying when you are factory resetting. It takes me on 5-7 attempts to successfully hard reset this phone.
Hard resetting / factory resetting your tablet will solve the following issues:
1. If you forgot your pattern lock
2. If you forgot your gmail account
3. If you forgot your password
4. Apps that automatically force closing
5. Stuck in LG LOGO(sometimes does not work if the firmware is totally damage)
NOTE: Performing hard reset will erase your data.
To hard reset:
1. Turn off your phone.
2. Press and Hold VOLUME DOWN + Power button. When it powers up, release the all the Button.
3. When you see the LG LOGO, press the POWER Button 3 times. After pressing it 3 times. It should bring you in a text mode with indication if you are going to factory reset your phone.
4. Just press the POWER Button and it will reboot and automatically wipe all your data.
I hope this tutorial helps you.. If you have any question just drop a comment.