On Monday morning I went to the office. There I connected the board to a Windows 7 machine. The status went to Ready from Programming imediatelly. In this way I was able to ugrade the bootloader and download the OpenSDA debugging firmware. The new bootloader (v1.11) stated imediatelly that the old one (v1.10) not compatible with the Windows 8.1. I was surprised on this a little bit. The problem is not new (http://pakahuszar.blogspot.hu/2013/12/windows-81-mired-freedom-2.html), but the board itself is a 2014 model. So I don't understand why Freescale wasn't able to put the corrected firmware into it.