Sorry, busy week. But I finally got it running again.
Thank you for your help.
Normally I use Suse, but I made an Ubuntu USB-stick. I installed libftdi1, libftdi-dev and the libusb-stuff. Then I downloaded the guruplug-installer http://www.plugcomputer.org/index.php/us/resources/downloads?func=fileinfo&id=65
Right after powering up the guru, I startet "sudo runme.sh openocd" and it worked!