These are the instructions to unlock bootloader on OnePlus 2 smartphone using the fastboot tools on windows computer.
Requirements: Your device should have atleast 20 percent or above battery to perform the unlocking process.
Step 1: Download and install OnePlus 2 USB driver on your computer. If OnePlus 2 USB driver is already installed then skip this step.
Step 2: Enable USB debugging on your device. To enable USB debugging: Open Settings > Developer Options > USB Debugging > Tick to enable.
(Developer Options is hidden in Android 4.2.2 or above, to show this option: Go to Settings > About phone > Built Number (tap on it for 5-8 times).
Step 3: Now, power off your device.
Step 4: Now, you need to boot into the Fastboot Mode. To Boot into fastboot mode, press and hold the Volume UP and Power Key (for 4-5 seconds) and release all the the buttons when you are able to see the fastboot logo on the screen.
Step 5: Connect your OnePlus 2 smartphone to the computer.
Step 6: Download and install Minimal ADB and fastboot tools on your computer.
Step 7: Once, installation is completed launch the Minimal ADB and fastboot tools.
Step 8: Now, you will be able to see the following command window.
Step 9: Now, in the command window type and press enter: fastboot devices
(from the above command you will be abe to see the list of devices attached to the computer)
Step 10: Now, give another command: fastboot oem unlock
Step 11: Now, you will be able to see the verification screen on your device. Simply choose Yes by using the volume down button and press power button to confirm it.
Step 12: Now, your device will reboot automatically.
Congratulations, You have successfully unlocked the bootloader of your OnePlus 2 smartphone.
[*] Caution: Unlocking the bootloader will delete your personal data, pictures, apps etc from your device. So, take a backup of your personal data before following the above tutorial.
[*] Root OnePlus 2: If you want to root your OnePlus 2 smartphone then follow How to root OnePlus 2 tutorial.
[*] OnePlus USB Driver: If you are looking for the original USB Driver for your device then head over to Download OnePlus USB Driver for all devices page.