To all i have made a lot of test and without other box, you can only use SRS samsung remote client unlock,this is a free software and can change the serial for free!It's crazy that z3x team can't do this and using a cable and this software is possibile.
It's very strange because all modifications consists only to modify nv_data bin and here are store all data like imei,BT,serial,wifi,ecc and all are encrypted.
I'm a software engineer and i haven't spend a lot of time to check what type of encryption use samsing but i think is the same to change IMEI and SERIAL and so why z3x can't do it?ANd if can't do why don't block option?because you can choose only 10 char and not 11.
However use always i9100 option to change data like BT WIFI and PRODUCT code and remember to check COM and not USB during repair option.
However i use always this software to change serial and it works.
However change serial ins't needed because ariza patch can get you network with serial 000000 to but if you have to do this job for a customer (like me) it's not good see in info serial 00000000
To use this software you have to pay nothing!just login as test with username and pass written on software.
Connect phone with usb and click on advanced option.
Now insert imei and serial (both are needed) and make it.
Now your serial is 100% good and sometimes you need to repir imei again with samsung tool.
However remember to use i9100 option,with i9300 you can't repair product code ,wifi ,etc (programming is my job too and i don't understand how z3x engineer works)
And remember to have good results it's almost needed to make a downgrade
100% WORKS and Thanks me

yes now you can repair imei i9300 with original imei or not original imei: work network yes
At first I will re-process change imie .this time type imie as you like original or not-original ( If you had written the original will not need to patch in the end the subject. but sometimes the network does not work with original imie)
1. Select Model i9100 and Select port
2. The first arrived USB in Mobile. on repair choose com press pepair
4. Type imie no. press ok
5. After Rebooting phone .. remove the USB cable. Put cable RJ45
if the network not work Follow the following
download this file http://www.arizandroid.com/patch/ariza_JBv02.zip and copy it your sd card by using volume up + home + power buttons get into cwm menu and than
- install zip from sd card
-choose zip from sd card
and select ariza_JB02.zip
- please wait automatic reboot
This everything
Thanks to the owner of the patch arisa 27
There are some observations can be learned in the original position of the Patch, but I need only patch to solve the problem of network
[SOLVED]Network problem after the update and sn 0000.. Problem- solved !!! - xda-developers
Note Finally, if updated device worked or installed new software needs to install the patch again
Today I am very happy for repair problem imie Samsung Galaxy 3
Thanks for all