Follow the original instructions posted everywhere, but be aware of the following differences.
When you try this you will NOT see the big red box on screen. You will only know itís doing something else by the fact the screen res is at the lowest.
After you get to that point, and have rebooted back with the 2 files on the usb drive, the HDD light may not flash, but the usb light will. The power light will eventually start to flash green, leave it alone for 10 minutes then turn off using the front power button.
When yu turn it back on you will now see the red box and you are now a retail unit.