How to Unlock the Bootloader on OPPO F21s Pro 4G

The vast majority of OPPO F21s Pro 4G owners are not aware of the feature called the "bootloader". Some people may confuse it with the standard Downloads application, through which files can be downloaded from the Internet. But advanced users know about this term and understand that they need to unlock the bootloader on OPPO F21s Pro 4G.

What is a Bootloader and What is It Used For

For a start, it's worth discussing the bootloader itself. Bootloader is the engineering menu of OPPO F21s Pro 4G, which functionally resembles the BIOS on a computer. It allows for deep-level manipulation of the smartphone, not just a factory reset.

By default, the bootloader is locked. This is done so that novice users do not make a fatal mistake when editing the device kernel or brick their OPPO F21s Pro 4G. Still, unlocking the bootloader gives the smartphone owner the following benefits:

the ability to install custom firmware;
root rights for extended access to the device;
installation of mods and patches for the current version of the OS.

Generally, unlocking the bootloader provides the user with a lot of features, but only experienced users can fully appreciate them. If you are one of such users, then it is recommended that you read the detailed instructions for unlocking the bootloader.

Precautions

Before reading the guide to unlocking the bootloader, you need to take into account a number of dangers inherent to the operation. First, after its completion, OPPO F21s Pro 4G will be automatically void of its warranty, as in the case of obtaining root rights.

Second, after the bootloader is unlocked, system components will become more susceptible to all kinds of threats. Finally, an unlocked phone can be easily recovered by an intruder who has stolen or found the device on the street.

Unlocking the Bootloader on OPPO F21s Pro 4G

After reviewing the aforementioned info, you can proceed to the procedure itself. It consists of three stages, each of which needs to be carried out by the user.

1. Status Validation

First you need to understand if bootloader is actually locked on your OPPO F21s Pro 4G. After all, it is possible that you purchased the device second hand, and the previous owner has already performed the appropriate steps.

The check is carried out by direct interaction of the phone with the computer. The steps are as follows:

Download and unzip the ADB and Fastboot debug bridge package to your PC.
Download and install the driver to interact with the smartphone using the official Android website.
After installation, the ADB interface should be displayed in the Device Manager.
Put your smartphone into fastboot mode by first turning it off and holding down the volume down key along with the power button.
Connect your mobile device to your computer.
Launch Command Prompt on your PC.
Enter the following: "cd [path to the adb and fastboot folder]" and press Enter.
Use the "fastboot devices" command to detect the phone connected to the PC.
Enter the prompt “fastboot oem device-info” to determine the bootloader status.

In the information displayed by the command line we will be looking for the line "Device unlocked". If the value opposite it is "false", it means that the bootloader is locked. If “true”, bootloader was unlocked earlier.

2. Sending a Request

To remove the bootloader lock on OPPO F21s Pro 4G, you need to send the corresponding application to the manufacturer:

Open the official website of the firmware developer.
On the unlock page, click the "Unlock Now" button.
Authorize your account (it was created when the phone was first set up), and indicate the reason for unlocking (for example, for flashing).
Confirm ownership of the device using the code from the reply SMS.

Then you will have to wait for the manufacturer to approve the request, and you will be able to use all the functionality of the bootloader.

3. Approval of the Application and Unlocking

To see if you managed to convince the manufacturer to unlock the bootloader on the OPPO F21s Pro 4G, open the request page. If approved, a confirmation will be displayed on that page.

Now the user will be invited to download the software for unlocking the bootloader. It is installed via PC.

Next, you need to open the phone settings, then go to the Developers section and select the "Factory Unlock" item.

In the "Status" you need to go through authorization to the account, which was indicated on the manufacturer's website.

Now put your phone into fastboot mode and run the downloaded software on your computer.

After authorization, you need to connect your smartphone to the PC and confirm the unlocking.

After a couple of minutes, the operation will be completed and the bootloader on the OPPO F21s Pro 4G will be fully unlocked.

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