I'm not going to do that, and I doubt most other people would be willing to give you their efs folder. I understand the predicament you're in and I'm sure you are well-intentioned, but this would give your phone the same IMEI as my phone. First off it is illegal to have two phones with the same IMEI, second you could potentially report the IMEI stolen and lock my phone or worse. While I don't think you'd be malicious it, I'm just not comfortable giving it to you.
This would be very similar to somebody giving you a copy of their license plate from their car because yours fell off. It's just bad idea.
Since Odin won't work (it should), I suggest calling Samsung support and tell them you received an OTA update via AT&T and your phone doesn't work. Unfortunately you're going to have to lie and tell them that you were in the United States on AT&T's network, but hopefully you can send it in for a warranty repair.
In the future (I'm assuming you bought the phone for full price and it isn't subsidized by your carrier), always buy the international version of a phone with an unlocked bootloader. If you're paying full price for a phone there is no reason not to buy a bootloader unlocked phone because you would have a lot more options if you run into problems. Sorry I can't help, but hopefully you are able to resolve your proble.