That feels very risky, but I’m glad it worked!

What was the backup plan if something went wrong?

From what I remember of using Odin a decade ago.. it doesn't actually 'flash' the device, it copies the binary blobs to the bootloader partition and tells the device to flash itself from them, then reboots the device. So it should be relatively safe under wine, it'll either work, or it won't.

It was my own. I'd have to get it to a repair shop.