Unlocking the bootloader on the HTC One M9 is now possible through the official HTCDev website. As you may already know, once the bootloader on your device is unlocked, you can install a custom recovery, try out various custom ROMs, and do literally anything on your device without any restrictions.
The following tutorial should you walk you through the steps to unlock the bootloader on your HTC One M9:
Files You Need
1. This should erase all the data stored on your device. Make sure to take a backup of your files before you proceed further.
2. Download Minimal ADB Setup to your computer. You’ll use it to issue commands to your phone.
3. Download and install HTC Sync and it’ll install the required drivers on your computer.
Unlocking the Bootloader on the HTC One M9
1. First of all, extract files from the ADB archive to your computer. To do that, right-click on the archive and select Extract here.
2. Turn off your phone.
3. Turn your phone back on in fastboot mode. To do that, hold down Volume DOWN+Power buttons at the same time.
4. Once in fastboot mode, plug in your phone to your computer using a USB cable.
5. Launch a CMD window in the folder where you have saved the ADB files. To do that, hold down Shift and right-click on any blank area on your screen and select Open command window here.
6. Type in the following command into the CMD window and press Enter:
fastboot oem get_identifier_token
7. You should see a long string in the window. Copy it to your clipboard.
8. Now, head to HTCDev website, sign-up, and click on Unlock Bootloader.
9. Paste the string you copied in the previous email into the box on the HTC site.
10. You should get an email from HTC with a .bin file. Download the file to the folder where the ADB files are located.
11. Now, issue the following command using CMD:
fastboot flash unlocktoken Unlock_code.bin
12. It should unlock the bootloader on your device.
13. When it’s done, reboot your device using the following command:
14. You’re done.
And there you go.
The bootloader on your HTC One M9 is now unlocked and you can head to our how to install a custom recovery on the HTC One M9 tutorial to install a custom recovery on your device.
Once a custom recovery is up on your device, you can then gain root-access by flashing the SuperSU archive.