Try pm bajanman. He has the at&t variant which is similar but he is far more knowledgeable than me. You might need to edit your efs folder with a root browser
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Hi sir, I also have the same problem but my note 2 is a korean variant SHV-E250L. I also lost my IMEI and the baseband version is unknown when I flash it with 4.3 stock rom via odin. Now I can't use my phone I was also considering on changing its mother board but I cant seem to accept the fact that it can never be fixed without changing its mother board. I cant even revert back to 4.1.2 because of the 4.3 secure bootloader issue. Odin keeps failing it says "Unsupported version". I really hope that you can help me to fix this problem. Thanks.