Yep, you're right. Getting the phone to successfully take a stock rom flash via Odin is the only way you're fixing it. How ? Search for Hopper8's 'Odin troubleshooting' thread. Try the stuff in the that thread. I'd be very surprised if you can't get it working normally doing that.
Edit - Doesn't matter which stock rom you use, that has nothing to do with the flash working/not. Any stock rom will do.
If it's important enough to cause you grief if it's lost, back it up. No excuses
Trolling for thanks is lame
Does Samsung's auto-brightness implementation crap drive you to self-harm ? A solution !
Most retarded thread on XDA in 2013