I kept running into issues rooting my S9 (SM-G960F), so I decided to just fully re-flash the stock firmware, but that just keeps getting stuck at Vendor. Please help me get my phone flashed back to stock.

Hello,

I followed this guide here on reddit, which claimed you could root the phone just by flashing TWRP and then a couple other files, after various YouTube tutorials failed to work. It unfortunately also did not work, as it only granted SuperUser within the first minute of rebooting, and then never again until the next reboot. So I tried downloading the stock ROM and using Magisk to patch the boot image, but that changed nothing. So, because I already had the stock firmware downloaded - definitely the correct one btw - I just used ODIN to re-flash it back to stock. Well, I've tried 4 or 5 times now, and, no dice. It quickly goes through the first half, and then once it gets to vendor.img, that's it. It just stays that way indefinitely. I've tried waiting 30+ minutes, but nope, nothing happens. I am unable to boot into recovery to try a factory data reset, because the phone just says there was an error during update and I need to use the emergency something or other on the Smart Switch PC program. I'm using Windows 10, and have also tried windows 7, same thing happens on both.

If anyone knows a surefire way to get this thing back to working, I would really appreciate it. Thanks in advance!