As an update I am still working on this problem.
The good news is I can now fix this problem but only by using a new, mechanical Toshiba HDD. Dead Bose NITs can be brought back to life - this has not been done before. Also I can upgrade the software from v1.07 to v2.00 software and take Gracenote from 2008 data to 2009.
The bad news is I am as yet unable to do this on a SSD nor enact any of the hacks I want. Bose and Maserati have all refused to help multiple times. This has all been borne from tenacity and the kindness of Keano lending a (mostly) working drive.
To cut a 6 week/200 hour sweat, blood, toil and tears story to a nutshell: Bose used a proprietary military grade filesystem (?!?!). It was done for redundancy to ensure read-write survivability in high-end use cases and you see similar in HF trading databases. The result however is there is NO way to see/recover/fix a corrupted drive. I identified and have spoken with the Bose & filesystem lead software developers from the time. I have spent a lot of time at hex-level/raw data (which is how I discovered the filesystem type in the MBR). No software recognises the MBR or partitions because to the rest of the world they do not exist. We cannot buy/access the proprietary filesystem drivers to mount the system.
While we cannot see into a filesystem I do have a working v1.07 system. I also have the official update disks Maserati made based on UBoot images. I am hacking an official Maserati update CD to create a new ISO to inject a 2014 Gracenote database (instead of 2009) to see if we can have a v2.00 image with 2014 gracenote data. There is no visibility on the navigation data in order to inject new data.