I have this problem (software error) on my 4000nex. I know how to get the internal SD card out - I've already done it. If you have a backup image that's suitable I'd love any assistance you can send my way.
The internal card is a cheap-ass Transend 4GB, btw. What kind of idiot engineers at Pioneer chose SD memory as a long term storage solution? Most raspberry pi users know if you hammer the SD card (by swapping on it, for example) it'll fail pretty quick, sometimes within days.
Thanks if you can help, asd255. Or anyone else out there.
C