I had the whole product code issue when I flashed to JPC starting with O2U and JPC took me to KOR... and with some tinkering I now have an XEU device! I managed to edit my product code using the method detailed below. I have a feeling that the JPC update only changes the product code of a device isn't XEU or KOR already... I'm not entirely sure, but when I flashed to JPC with O2U it changed my product code to KOR... when I flashed to JPC after using the method below it now registers as an XEU. I don't know if flashing after this fix is necessary (it may be needed to re-write csc files?!?)
Please appreciate that I am not a developer, but a tinkerer! I used adb rather than EStrongs... but have written these instructions to use estrongs for the ease of those who aren't familiar with shell commands.
You will need:
Root Access to your Phone
a Hex Editor (there are a few free ones on download.com)
Estrongs File Explorer (from Google Marketplace, cause it has root access and means you won't need to use terminal (hopefully))
1a) in Estrong, go to settings and enable both root options
1b) Use Estrongs to navigate to the /efs/ folder on your phone.
2) Copy "nv_data.bin" and then paste it to your sdcard.
3) Mount your device to a computer and then make a copy of "nv_data.bin" and rename it to "nv_data.bin.bak" and leave that un edited on your sdcard (that way you have a contingency to return to should everything go wrong!).
4) Open "nv_data.bin" with your hex editor and use the find command to locate any occurance of 'KOR' in the file.
5) Replace each occurrence of KOR with the code your choice, be it ORA, XEU, O2U, etc.
DO NOT ADD ANY EXTRA CHARACTERS AS THIS MAY RENDER THE FILE UNUSABLE BY THE ANDROID SYSTEM
6) Save the file and then unmount your phone.
7) Use Estrongs to copy the "nv_data.bin" from your sdcard back to the efs folder overwriting the old "nv_data.bin" file
8) Reboot the phone (push and hold the power button for 10 seconds or yank the battery your choice!!!)
9) Hook up to Kies and check the registry entry to make sure it worked!
Hope that helps.