Apple Watch series 8 cellular stuck at boot loop

1. Are there any DIY methods to reinstall or recover watchOS on a Series 8 without an Apple developer dock or sending it in?

2. Could this still be a hardware fault (e.g., failing S8 SiP or NAND) despite the repair shop’s opinion?

3. Any experiences with third-party services that can re-flash or re-pair watchOS safely in Australia?