Unfortunately, the FreeBSD boot loader doesn’t work on fit-pc, though apparently loaders of other BSD’s and Linux’s GRUB work withot problems. Yay for FreeBSD. I tried many things, including using GRUB (which boots the pre-installed Ubuntu), without luck. I agree with the diagnosis proposed by other similar users: something in the loader disables USB in the middle of booting. At the end, I took its drive to another machine, installed FreeBSD there and returned it.
FreeBSD is not exactly a good choice for fit-pc. There are no drivers for its USB 2 (USB1 works) controller, its audio controller and its built-in hardware crypto acceleration (AMD Geode AES). All of these things work on Linux. On the other hand, at least the network ports (Realtek chip) and other basic components (IDE controller, motherboard devices) work.