so focusing on the digital backups
That file is basically empty from the looks of it. If the repair tool couldn't pick anything and the header is all 0s, this is my current conclusion. Do you have other backups (that were not on the device you saved these files on?)
and I'd like to compare if the paper backups are missing anything that the digital have (ie derivative addresses using that aren't loaded in the paper backup, that either had transactions and a nil balance now, or some small balance left over).
Restoring from a paper backup creates a 1000 address lookup. Regular wallets start with a 100 address lookup, and rarely do users go over that. It is highly unlikely 1000 address won't cover your entire history. At any rate, you can create 10k addresses just to make sure.
I also noticed something else. I have the first attempt in a sub folder on my desktop, so I thought that it might be to do with the path length
MAX_PATH on Windows is 32768. Length is probably not the issue. Look out for non ascii characters in the path instead.
Also, I noticed that when you have no wallets set up and try and load a wallet, this happens
You saying trying to run the repair tool with no wallet loaded hangs?
After this I get failed to fix, invalid path or file isn't a valid armory wallet.
Refer to the first comment.