Connect a USB cable from the OTG adapter to the phone.
From the Termux terminal, command the target device to restart into its bootloader interface: adb reboot bootloader Use code with caution. unlock bootloader using termux better
fastboot oem unlock UNIQUE_KEY
A prompt will appear on the Host device asking to grant Termux access to the USB device. Grant it. Connect a USB cable from the OTG adapter to the phone
You still need two devices: a host Android device running Termux and the target Android device to be unlocked. You cannot use Termux on a single device to unlock that same device's bootloader, as the target device must be booted into Fastboot mode, rendering its own operating system inaccessible. Grant it
To understand why this method works, you must look at how Android handles developer utilities. Termux is a terminal emulator and Linux environment setup for Android. Because Android is built on top of a Linux kernel, Termux can native-compile and execute binary files originally meant for Linux desktops.
Connect your OTG cable to the phone running Termux. Plug your data cable into the OTG adapter and connect the other end to your locked, powered-off target device. Step 2: Prepare the Termux Environment