Chosen Solution
My LG G STYLO bricked itself, and keep showing secure booting error,
Download and Install LG Android Drivers On your PC Make sure have Unlocked bootloader of LG G4. Make sure you have installed TWRP In LG G4 Download the custom ROM file, Doc_Test.zip from the given link Now Connect your LG G4 to PC. Transfer the Rom zip file to your LG G4 internal/external memory Reboot into recovery mode. Flash custom ROM now. In TWRP recovery, tap on Install, and then browse to ROM file(Doc_Test.zip) and tap on it to select it for installation. On next screen, just do the ‘Swipe to Confirm Flash’ to install root on LG G4. You will get Successful written in blue text on next screen, tap on Reboot System. Wait for the device to boot up. Get more support from LG G4 Manual.
