Mr. Obvious says: wouldn’t it be professional, helpful - and good PR - if someone from (long-disbanded) LG G5 design team and/or tech support weighed in with an official solution, or even an insider’s unofficial kluge? Try to find someone on LinkedIn, twitter, Facebook? Perhaps an experienced 3rd-party tech? (Backup/wipe/restore seems a pretty risky experiment, never mind screwing around with internals.)