In conclusion to this thread, what seem to be the available options to me are to recover via ADB, or solder out the flash storage and try to connect it somewhere and read it.
Given that on bootup, you can only the volume and power buttons to do anything, you are limited to select from the Main Menu options, one of which is 'Connect with MIAssistant' although this has never got me any where. Maybe the CIA would have their own version of MIAssistant to gain assess...
I'll mark this topic as solved since I can't find any way to progress the problem.