WD should provide a tool, made by this guy, to help all the people solve this problem in the event of a failed external case. This guy deserves to be contracted by WD and receive big money from them. After a few minutes of sending the disc blocks containing the key to Thomas, he was able to point me with the unscrambled key and how to use it in Linux (I used Ubuntu Mate). This board has a Symwave SW6316 chipset which applies hardware encryption of AES-256 to all data. I testes with different power supply and USB cable and nothing worked.
The USB-to-SATA board fried and did not start the disc, nor it got recognized by the computer. It was a MyBook Essential 2TB USB3.0, model number wdbacw0020hbk-00. I want to say to everyone that Thomas Kaeding helped me save all the data from a friends hard drive.