Yup, congrats are in order!
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Guinea pigged my PW2 for science!
As for blocking updates, the folder trick *might* still be usable. AFAICT, the base temp file name has changed (/mnt/us/update.bin.tmp -> /mnt/us/update.bin), and the system *might* only be killing the old filename? Not quite sure where the .partial came from and if that's still in the cards though, so, pure conjecture here
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In any case, massive thanks to Branch Delay for persevering, and being successful in the end