First, you should have post this question in original discussion [Only registered and activated users can see links. ].
Second, it seems that you misunderstood tutorial.
It is not JNX file to change, but you must change CID on "CID changeable SD card" as stated it title of that tutorial, according to serial number in JNX file.
For that you need "CID changeable SD card" and "CID changer program".
In this tutorial is not explained how to change CID of SD card, so you will have to learn it by yourself.
I'm not too much familiar with that, but you can search in [Only registered and activated users can see links. ] where it is very common and discussed many times.
Maybe you can find some tutorial or explanation there.
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