This article explains how to unlock the bootloader on an Android phone.

• The Fastboot tool is one easy way to unlock the Android bootloader.
• Some phones require an additional unlock code from the manufacturer to unlock the bootloader.

How to Enable OEM unlocking

Before you can actually unlock your phone, you need to enable the OEM unlocking developer feature in Android.

1. Open the Settings app on your device.
2. Select About phone.
3. Near the bottom of the screen, you see the Build number. Tap it seven times to enable the developer options. You may be prompted to enter your password to continue.
4. Go back and choose System in the Settings app.
5. Locate and select Developer options. Developer options are likely in the Advanced section. Tap the down arrow to open those options.
6. Find the OEM unlocking option, and toggle the switch on.  
7. Scroll down and locate USB debugging. Toggle the switch on.

How to Install Android Tools

Enabling OEM unlocking only makes it possible to unlock the device. In order to actually unlock it, you’re going to need a couple of Android developer tools from Google. These are freely available, and they’re simple to use.

Windows

1. Download the latest Android tools ZIP for Windows.
2. Unpack the ZIP file into a convenient folder. This is the folder you will run the tools out of, so it should be fairly easy to access.
3. Right-click the folder containing the extracted files. When the menu pops up, select the Open command window here.

 Ubuntu/Debian Linux

1. Open a terminal window.
2. Use ‘sudo’ to get root privileges, and use the following command to install the Android tools.$ Sudo apt install android-tools-adb android-tools-fastboot
   

How to Unlock With Fastboot

You’re ready to unlock your phone’s bootloader with the Fastboot tool that you just downloaded. Before you go any further, you should see if your phone requires a code from the manufacturer to unlock it. Here are the instructions for several major phone manufacturers:

• LG
• HTC
• Motorola
• Sony
• Samsung (Only international Samsung phones with an Exynos processor can be unlocked.)
• Google phones can all be unlocked by default unless you purchased them from a major carrier.

Plug your phone into your computer with its USB cable.

In the terminal (or Command Prompt), run the following command to connect your phone.adb devices
You’ll see a message requesting access on your phone. Check the box to always allow the connection, and confirm.

Run the following command to reboot your phone into the bootloader.adb reboot bootloader

Wait for your phone to reboot. You’re now ready to unlock with Fastboot. On newer devices and Google devices, run the following command:fastboot flashing unlock
On devices that require a code—or, possibly, some older devices—run this command:fastboot oem unlock
Omit the code, if you don’t need one.You may be asked to confirm. Do so.

After you see a confirmation message that your bootloader is unlocked, you can reboot it with Fastboot.fastboot reboot

As your phone reboots, you’ll probably see a warning that your bootloader is unlocked and that it isn’t secure. Continue booting. Your bootloader is unlocked, and you’re ready to continue flashing a custom recovery and rooting your device.