On this page, you will learn how to unlock the bootloader on your Symphony SL20. Using the bootloader you can install custom ROM, custom recovery, custom kernel, and flash the factory images, etc. The bootloader will help you to unlock your device legally binding, but it will affect the device warranty. Symphony doesn’t allow you to unlock the bootloader. Mostly Android OEM manufacturers lock the bootloader, if you want to install any CUSTOM ROM, you must need to unlock the bootloader of your SL20. It will void the warranty.
Symphony SL20 Unlock The Bootloader Quick 10 Steps
Firstly, you need to enable the Developer Options on your Symphony SL20.
Go to Settings->>About Phone->> and press the Build Number 6 to 7 times until you see a pop message that shows you “You are now a developer”.
Into the Developer Options, now you need to Enable USB Debugging,
and the OEM Unlock Option.
After that, again head to the Settings>>>>Developer Options>>>>enable USB Debugging and OEM Unlock.
Download and setup the ADB and Fastboot tools
on your Computer.
Now, connect your SL20 to your Laptop/PC using a USB cable.
Now, you should wait until all the USB Drivers
installed on your computer.
Now open the CMD or command prompt and go to the same folder, where you have extracted the contents of the ADB and Fastboot tools.
After that, type the below command into the command prompt area and press the Enter button;
You will see a popup message on your smartphone such as “Always allow from this computer”. Now You can press the OK button.
You should type the below command to enter the bootloader mode, and press Enter; button on your keyboard.
ADB reboot bootloader
Now, you must enter the below command so your SL20 and you will reboot into Fastboot mode;
Fastboot flashing unlock
Now, enter again your device into the Fastboot mode using the Volume Down + Power button together.
After that, enter the below command;
Fastboot flashing unlock_critical
That’s It! You have successfully unlocked the bootloader of the Symphony SL20 device.