This Firmware file you can use this flash file when your device hang on logo problem, restarting problem, security lock problem, password lock problem, pattern lock problem etc software related problem and you can use this tutorial without any box and this is free for all who know about software in mobile, impotent for flashing first must check your micro usb cable if not good then you can't flash it so check micro usb cable second check your device battery that is impotent for flashing if your device battery low so stop your device between flash so this is impotent for flash, before you flash save your data like contact, photos, videos etc because this is factory flash file so you can't save after full flash so must remember all are impotent notes.
Required for flashing:
1. LG G4 device with good battery charged
2. LGH815V20A 6.0 Firmware
3. Lg Flash Tool
4. LG Drivers
5. Micro usb cable
6. Computer or Laptop
Procedure:
1. Download firmware or flash tool from above link (if link not working just write down comment on below comment box)
2. Extract to both files to desktop or as you like path (must be installed to winrar in your computer or laptop)
3. Turn off device if your device on
4. Press and hold both Volume keys and Connect Micro usb cable screen will show Download Mode
5. Update the driver if not installed in your computer or laptop
6. Open LG Flash tool 2014
7. Choose CDMA option from Select Type
8. Choose CS_EMERGENCY option from PhoneMode
9. Click on Select KDZ File and choose H81615xxx_00.kdz file
10. Click on CSE Flash button (See below image for more know)
11. Now open second windows screeen
12. Click on Start button (see below image)
13. Wait until full install (do not unplug while your device in download mode)
14. Congratulation you are done