With your solution I could solve the problem. Thank you very much!!
The next crucial step is for installing the image that has already been downloaded to the smartphone:
Press the buttons together: “On/Power”, “Home/Bixbie” (bottom left button) and “Volume down” until the device is switched off. A black screen appears. Then switch IMMEDIATELY (!!!) from the “Volume down” button to the “Volume up” button. Be sure to keep the “On/Power” and “Home/Bixbie” buttons (bottom left button) pressed(!!!)
The description should be also changed in the Easy-Installer to become really easier. 