[LG Optimus L9 P760, P765, P768, P769] shucrut:
Hi,

First of all, i have no credit for almost things i'm gonna say here, thanks must go to who realy worked in the mentioned things.

I created this thread because of the large numbers of people in [Q&A, Help & Troubleshooting] and realized that the most of these problems could be solved with a simple guide. I repplied this in a thread but now i'm creating in general with hope that people sees this before asking again.

This guide can be used in these cases:

- Phone is not recognized by KDZ offline flashing

- Phone enters in

SECURITY ERROR

screen and doesn't boots up

- Fail trying to flash a new ROM and the phone doesn't starts

- You tried to install custom ROM via CWM and your phone have a

LOCKED

bootloader

- You tried to install a custom recovery via fastboot/adb and your phone have a

LOCKED

bootloader

- Anyway, if you think your phone is dead, give a try here

When you try to install a custom recovery with your bootloader locked (for example), the phone system detects it and give you a message of an error in security. To solve this, you'll need to reflash your rom. By doing this, the KDZ will reflash the original recovery and you will be able to access your phone/recovery again.

Step by step:

1. You need to install fastboot drivers: http://xdaforums.com/showthread.php?t=2119090

Turn off the phone and remove the battery. Download THIS and exctract it to C:/. Open device manager in windows (Rigt click on Computer > Manage > Device manager) and connect your phone without the battery to pc via USB cable. Look in device manager for a new hardware connected, right click on it and click in update drivers. In the window open, select "Search for software driver in the computer" and in the window open select insert C:\fastboot\usb_drv_windows, tick the option "include subfolders" and advance. A pop up window may appear asking you if you do want to install the driver, choose YES and the drivers will install.

1.1 - If you're having some badtimes installing fastboot drivers, follow THIS, it will probably solve the most of the problems - thanks [MENTION=4447066]kuma82[/MENTION] for catching it :D

2. Navigate to the folder you extracted (C:/fastboot) and double click on start.bat. It will ask you for administrator privileges, just say yes.

3. Select your phone model (2 for P760, 3 for P765, 4 for P768 and 5 for P769). It will ask you to turn off your phone and remove battery. When you done with that, press enter. It will now ask you to insert USB cable with the phone without the battery and after 4 seconds re-insert the battery. Onde you done with that, it wil return a message to press any key. In this step the fastboot drivers may be installed again. Don't worry, it's normal

4. Remove the battery again, wait a few seconds and re-insert it.

5. Plug the USB cable in the phone with the battery in and let VOL UP pressed. The phone will enter in SW Update mode.

6. Follow THIS to reflash your rom. A list of avaiable official roms of different models is HERE. Remember to only flash roms made for your phone model or you may get some issues.

7. You're all done I recommend using THIS TWEAK, the phone becomes more responsive.

*** If you flashed a JellyBean rom (V20X.kdz) you can easily root with THIS and if you want CWM recovery use THIS CWM FOR LOCKED BOOTLOADER ------ REMEMBER NOT TO FLASH ANY CUSTOM ROM WITH THIS RECOVERY BECAUSE I'M CONSIDERING YOUR BOOTLOADER IS LOCKED AND FOR THIS REASON, YOU CANNOT FLASH CUSTOM ROMS WITH CWM, IT JUST DOESNT WORK!!!

People who deserve thanks:

[MENTION=4254774]sguerrini97[/MENTION]

[MENTION=4448971]cmahendra[/MENTION]

[MENTION=4489107]Dragusdrake[/MENTION]

[MENTION=2962874]captaincrook[/MENTION]

[MENTION=3519950]artas182x[/MENTION]

[MENTION=2159458]Lelus[/MENTION]