It seems to be safe to modify this file, so long as you take a backup of anything you are about to mess with. I would suggest taking 2 backups, just in case...
If so, get a hex editor and look at address 0x181468 (that is in hex). If you are locked, you should see "FF 01". If you are unlocked, you should see "FF 00".
1) Can people confirm this to be true? In my limited sample, it's true.
2) If you change that to "FF 00", and replace the file (with backup), does it work as unlocked, or does it just not recognise the radio?
3) If not working, restore the file you created, and delete the nv_data.md5 file (be sure to back it up as well before doing anything). Again see if it works.
4) If you don't get your unlock sorted (if you do, free unlock and congrats, please let us know what you did), then restore the old files and you should be back to normal.
Also... If you feel really bored, how about dumping the nv_data.bin BEFORE and AFTER flashing a kernel via ODIN, such that the counter on download mode increments. The idea being to see if this file changes when flashed... Obviously you need to label the before and after clearly, and give the value of the number for before and after
For emailing any nv_data files to me, my email is: