[G4 Q&A, Help & Troubleshooting] luckysingh111:
Hello,

I recently post a thread regarding my lg g4 f500l has no display after flashing Europe rom and find no reply. But i manage to grab some info and help from different forms and combine them to revive my lg g4 which has no display, no download mode just blank screen i tried putting it in freezer and disabling big cores but no avail and unable to flash back to f500l through LGUP and lgflash tool 2014 because invalid kdz file.

NOTE:- MY LG G4 WAS WRITTEN AS H815 ON THE BACK STICKER THAT'S WHY IT HAPPEN TO ME :(

Flash Guide https://xdaforums.com/g4/general/guide-lg-g4-stock-firmware-to-stock-kdz-t3107848

So here what i did i found a thread flashing different kdzs by changing their name in hex editor so what i did i open F500l F500L20C_00.kdz with HxD hex editor which is free and press ctrl+r to search and replace F500L with H818N all the entries and save the file at desktop. And people who has no download mode remove your phone battery and attach a usb cable with pc your phone will show no battery icon so press vol up button and insert the battery at the same time lg logo will flash and you will go into download mode. it may take few tries though. now open LGUP and flash your modified kdz it will flash without any error... So your phone will boot up :) and will have display so you can setup your phone.

Ok as now you have working phone but still want to remove this Korean crap like me without having black screen i have simple method as you can flash any kdz even a dual sim one in single sim like me :) because for Indian network bands. Just download any kdz you want to flash from here http://storagecow.eu/index.php?dir=Xda/LG+G4/ for marshmallow i am not sure but it will also flash. After download open the kdz in WindowsLGFirmwareExtract-1.2.6. link in description now open up firmwareextract and select kdz and just extract only .dz file after completion select dz file option and select the extracted dz file click on file name so all file will be selected now click extract DZ you will have so Manny bin files. After extraction select Merge System.bin option so it will merge all bin files in one System.img file in merge_output folder of firmware extractor. So now you have the system file copy it in you lg g4 internal memory.

Now extract LG_Root.zip and and in extracted folder hold shift and right click and select open command window here. now open ports.bat file and see the port no of lg g4 the diaz1 one or you can see in LGUP tool either way note it down and close the ports windows now restart your phone in download mode by holding power up while connecting it to pc. Now in the command windows in pc type

Send_Command.exe \\.\COM12

COM12 is the port no you will get in ports.bat file make your you chose yours not this one.

now type id and press enter you will get some values if not disconnect and reconnect after that type

dd if=/data/media/0/system.img bs=8192 seek=65536 count=548352 of=/dev/block/mmcblk0

wait for some time till it come back on # and type LEAVE in caps your phone will reboot and you have new rom you will may get some error after booting just click ok or for avoiding them just hard reset your phone before booting just after type leave remove your battery and pu it back and press vol down + Power button when lg logo flash quickly release both and press vol up+vol down together you will be in reset menu just factory reset this process is for F500l only other model have different method or you can hard reset in setting after booting it you choice. So now you have a working g4 in any version kdz :) and you can also flashed rooted rom images found on XDA. So i hope you will find it useful. And our f500 bootloader is locked so cant flash twrp if anyone know different please tell me and how to flash custom rom on F500l it would be very nice of you.

Pre rooted bloatware free image https://xdaforums.com/g4/development/rom-rootedpure-image-g4-korean-f500-t3321855

And this is my 1st post of any solution and sorry for bad English :)