In order to root or install a custom recovery on your LG G4, you must first unlock the bootloader on it. An Android device with a locked bootloader cannot be installed with custom files, such as the recovery and root files.
Once you have unlocked the bootloader, the system partition on your device becomes writeable and that way you can get a lot of things up and running on your device.
In the case of the LG G4, the company officially allows you to unlock the bootloader so that you can then customize your device the way you want. So, here’s the procedure for unlocking the bootloader on the European variant of the LG G4:
Files You Need
1. Keep in mind that you will not be able to re-lock your bootloader once you’ve unlocked it. The official LG unlock method just doesn’t let you re-lock your bootloader.
2. This only works for the European variant of the LG G4 that has the model number H815. It doesn’t work on any other variants.
3. You should be running a Windows based PC to do this tutorial.
4. Download Minimal ADB to your computer. It will be used to flash the unlock code on your device.
5. Download and install LG USB Drivers on your computer, if you don’t already have them.
Unlocking the Bootloader on the LG G4 (Europe)
1. Extract files from Minimal ADB to your computer by right-clicking on it and selecting Extract here.
2. Head over to the official LG Bootloader Unlock page and get yourself logged-in (sign-up first if you don’t already have an account there).
3. Fill-in the information that the LG website asks you for. You can find out the IMEI number of your device by dialling *#06# on your device and you should see the 15 digit IMEI number.
4. You will also be asked to enter your device ID. To know your device ID, launch a Command Prompt Window where you extracted the ADB files by holding down Shift and right-clicking anywhere on the screen and selecting Open command window here.
5. On your device, head to Menu->Settings->About phone and tap on Build number for about 7-8 times and it’ll say you’re a developer. Then, head back to Settings and tap on Developer options. Turn on the option that says USB debugging.
6. Head to Menu->Settings->Developer options and enable the Enable OEM unlock option.
7. Plug in your device to your computer using a USB cable.
8. Now, type in the following commands into the Command Prompt Window that you launched in one of the above steps:
adb reboot bootloader
fastboot oem device-id
9. Just copy both the lines of the device ID without any spaces and make sure it doesn’t contain that “bootloader” part.
10. Paste this device ID on the LG website that you registered on in the second step.
11. You’ll receive an email with an unlock code. An unlock code is a file with .bin extension.
12. Download the unlock code file to the folder where the ADB files are located.
13. Ensure that your device is in fastboot mode. If it isn’t, issue the following command to get it into the fastboot mode:
adb reboot bootloader
14. Issue the following command to flash the unlock code file on your device:
fastboot flash unlock unlock.bin
15. When it’s done flashing, issue the following command to reboot your device:
16. Your device should reboot.
17. And you’re all done!
Congrats! The bootloader on your LG G4 (European variant) is now unlocked and your device is all set to be installed with a custom recovery.
Please follow our how to install a custom recovery on the LG G4 (Europe) tutorial to learn how you can get a custom recovery up and running on your LG G4 in no time. Once you get it done, you’ll be able to gain root-access which lets you enjoy many of the root-requiring apps on your device.