You sure there is an ext4 filesystem to be expected? (Just asking, no offence meant)

Otherwise I'd be keen to hear of any ideas from makrospex, I am getting a bit lost, the loop part still doesn't let go on me.

Just as some therapeutic exercise, could you post the output of

(I am really just fishing for new ideas here)

At this point I need to ask: Did this contain a wallet that you didn't have backuped otherwise or any other unique and valuable data or just a synched btc node that you want to get back online without synching from genesis?