I don't need help anymore. As said. I used the uboot present in an earlier version. I didn't try the serial, because there weren't even any screens (I thought there wouldn't be a serial either). The card seemed to just do a reboot Every 5 seconds (depending on the LEDs on the network card and the LEDs on the SSD which flash 1x. I'm not going to try again now that I have a working installation. I just wanted to share with you Other beginners who are not used to this kind of tools and not have the serial cable.
