[G3 Q&A, Help & Troubleshooting] NitritO:
Hi! im from Argentina, and my english is very limited:p and i like share my solution for this problem.

I use hide tool to facilitate step to step

Panoram:

1) When i did power my d855 can see LG logo and warning in top left of screen with the leyend "... Secure Booting Error! Cause: boot certification verify..."

2) If i push power + vol UP i see small iccon download mode, but i recived again "...Secure Booting Error! Cause: boot certification verify"

3) If i push power + vol DOWN wait 2 second and push again power + vol DOWN i can see the screen of factory reset, but i press YES and YES recive "...Secure Booting Error! Cause: boot certification verify"

GO!!

1)

a) Download TOT file and Unzip: lgd855at-00-v10b-twn-xx-jun-19-2014-32g+0.tot

http://storagecow.eu/index.php?
dir=Xda/LG+G3/Stock/D855/D855+TOTs/

b) go to post from genius user [MENTION=673006]l33tlinuxh4x0r[/MENTION] and download attach files:

http://xdaforums.com/sprint-lg-g3/general/guide-fix-hard-brick-recovery-guide-t3132359

Extract willcracker.rar and run this "WITH ADMINISTRATOR"

c) Go post from [MENTION=673006]l33tlinuxh4x0r[/MENTION] and GO to step 5 (remeber the "target dir" = "DIR" of image extraction)

In step 5: Go to image extraction

BIN = dir of TOT file

DIR = directory where extract image (you select one) and put this directory in "target dir"

and push extract (wait 10 minutes aprox, you can see dialog pop up "COMPLETE")

close willcracker

d) Instal dirver -"QDLoader HS-USB Driver_32bit_Setup.zip " or -"QDLoader HS-USB Driver_64bit_Setup.zip"

e) Extract Battery, hold power + Vol Up, pu battery, connect USB (you can see failed download mode and led blue and red) not push nothing, now hold 3 seconds Vol Up (if possible you listen a song of windows plug and play)

Open up Device Manager on your computer. Find "Ports (COM & LPT)", click on the tab on the left to expand it, you can see "Qualcomm HS-USB QDLoader 9008"

Now disconnect your phone

f) Go comand line and execute:

bcdedit -set loadoptions DISABLE_INTEGRITY_CHECKS
press INTRO
bcdedit -set TESTSIGNING ON
press INTRO

Reboot your PC

g) Extract Battery, hold power + Vol Up, pu battery, connect USB (you can see failed download mode and led blue and red) not push nothing, now hold 3 seconds Vol Up and verify if your device is detected how "Qualcomm HS-USB QDLoader 9008"

h) Execute willcracker "WITH ADMINISTRATOR" and go post of [MENTION=673006]l33tlinuxh4x0r[/MENTION] and complete step 6

IF you have LG G3 select the B2 in APCHIPSET

APCHIPSET = B2(...)

COMPORT=12 (remember step "g")

TARGETDIR=(directory you selected for extracrt tot image step "c)")

check box of "AP Check" and "EMMC TEST"

and click START and you get a "PASS"

i) Go post [MENTION=673006]l33tlinuxh4x0r[/MENTION] and complete step "8"

Check "RESTOREBOOT IMG" (see image from step 8) and select one for one:

SELECT

aboot

PRESS START

SELECT

Backupgpt

PRESS START

REPEAT

boot

dbi

laf

primarygpt

2)

a) Download driver

http://downloadandroidfiles.org/fil...leDriver_S50MAN311AP22_ML_WHQL_Ver_3.11.3.exe

Instal with administrator

b) In LG Mobile UsbSerial port press options>advanced and set por "COM41" and OK, OK

c) Downoad "FLASH TOOL"

http://downloadandroidfiles.org/file-php/?File=/Tools/FlashTool/Setup_LGFlashTool.zip

d) Open with administrator FLASH TOOL

Check box "Select Manual Mode"

e) Download Dll flash for LG D855 (unique dll from link)

http://storagecow.eu/index.php?dir=Xda/LG+G3/Stock/D855/D855+TOTs/

f) Press "---" and select dll from step "e)"

g) Press "Add" and select TOT file

h) Check box "UPGRADE DL" and "USB" and press OK

i) Press Yellow Arrow and wait for "READY!!"

j) Unplug USB, putout battery, hold power + vol UP, put battery, connect usb

k) When you can see number 3, wait 10 or 15 minutes, unplug USB and take out battery

CONGRATULATIONS!! Power ON your beautiful and revived phone and sing "SOY FELIZ"

Sorry my bad english!!