I've tried to unlock with Geohot's method and managed to revert it back. Here's how I made it:
1. Upload all the files after the unlock (including those generated) to a folder /revert113 on iPhone
2. Turn off CommCenter:
launchctl unload -w /System/Library/LaunchDaemons/com.apple.CommCenter.plist
Compare the seczone.revert with your original seczone, they should be exactly the same.
chmod 755 *
cat secloader seczone > fselector_revert
./iUnlock secpack fselector_revert
./norz seczone.ignore 0x3FA000 0x2000
./norz seczone.revert 0x3FA000 0x2000
4. Reflash modem:
5. Turn on CommCenter:
./bbupdater -f ICE04.03.13_G.fls -e ICE04.03.13_G.eep
Give it a reboot and everything's back to the original.
launchctl load -w /System/Library/LaunchDaemons/com.apple.CommCenter.plist