Lardman,
I tried the oz 336-pre and that gave me a root solely.  I wasnt really in the mood to play with the command line since I was looking for a decent gui... anyway, I ended up trying to flash 335, then the latest sharp rom.  
NOW  the powerup button (CANCEL) does absolutely NOTHING.  
I CAN atleast get into the Maintenance menu ... 
If I go through the update by USB choices it will provide a kernel error message saying something like 
modprobe: cant locate devinfo ... or something like that.
it can  reflash the ROM 
BUT... when I try to reformat it goes dead.   :x 
That\'s it! thats all this little sucker does.
Foxdie, there is no Nand option on the 5600 Maintenenace menu, so I guess Im screwed??!!??