SBC6845 SAM-BA hangs and no romboot prompt

Hi!
I have this SBC6845 single board computer form embest, which is a atmel 
at91samg45-ek based board.
I am trying to reprogram the nand- and data- flash with the sam-ba tool.
In the documentation it's said, that I should disable the nand and data 
flash by opening jp14 and jp8, connect the board with the host pc via 
the debug serial port, run a terminal programm (like picocom or minicom) 
start up the board, and try to connect with sam-ba.
First, there is no romboot prompt comming up in the terminal, and when I 
select the board in sam-ba and try to connect it hangs.

anyone who has experiences with this board or has an idea how to solve 
the problem?
thank's for replies.
HdcDst