[HELP] - Unable to unlock bootloader - Sony Xperia Z5 Compact - Fastboot FAILED

Hello Guys

I am stuck here and I don't know why this happens - to start off with, I would not consider myself new to this - so if I am just blind and dumb here, I'll be pretty embarrassed.

To start off with (all this should be self explanatory) - pictures say more than a thousand words;




Just for extra info; this is the steps received from Sony (IMEI), which I am sure that I followed correctly:

Code:

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Install the Android SDK and the device drivers

1. Download and install the Android SDK.

2. If you’re running Windows, you also need to download and install an updated Fastboot driver. This is the standard android_winusb.inf-file, with a few lines of code added to enable Fastboot to support Sony & Sony Ericsson devices. Replace the original android_winusb.inf-file with the downloaded file in the usb_driver folder, located in the Android SDK > extras > google folder on your computer. If you can’t find the usb_driver folder, make sure you are running Google USB Driver package revision 4 or higher in your Android SDK. If not, install the Google USB Driver Packager using the Android SDK manager.

Note! If you’re running OSX or Linux, you are not required to install any additional drivers.

3. On your device, turn on USB debugging by going to Settings > Developer options and click to enable USB debugging.
As of Android Jelly Bean 4.2 the Developer options are hidden by default. To enable them tap on Settings > About Phone > Build Version multiple times. Then you will be able to access the Settings > Developer options.
Connect to Fastboot

1. Turn off your Xperia™ Z5 Compact.

2. Connect a USB-cable to your computer.

3. On your Xperia™ Z5 Compact, press the Volume up button at the same time as you connect the other end of the USB-cable. For Windows users, when asked for a driver, point to the usb_driver folder where you placed the android_winusb.inf-file, and select the Android Boot loader Interface-file.

4. When your device is connected, open a command window on your computer and go to the platform-tools folder within the Android SDK folder.

5. Enter the following command:

fastboot devices

6. Verify that you get an answer back without any errors.
Enter unlock key

WARNING! The command below contains your unlock key. If you perform this step, you will unlock the boot loader. This may void your warranty and/or any warranty from your operator.

1. If you still want to unlock the boot loader of your device, enter the following command:

fastboot -i 0x0fce oem unlock 0xDFC4C30CD77A9B20

2. Verify that you get an answer back without any errors.

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The phone works perfectly, so it should not be a hardware issue, as far as I can see? and it looks like the drivers installed works fine as 'reboot-bootloader' worked fine (did this as a test to show some commands works).
Hope some of you have a fix for this problem.