Yes, you are right I just copied the whole flash from a different PRS to my one. But this looks like the best way because I didn`t know so much about the internal structur of the PRS650. If your have more information please share with other interested user. I know the conversion from a J-PRS to a PRS has a risk to brick my device and also that the warrenty is gone.
I don`t know if the serial number is really stored in the overwritten area because I didn`t compare it before and after modification. Normaly I would expect that this kind of information is stored in a kind of ROM area not changeable after production.
Do you know on which kind of information the DRM authentication is based? and where it is stored ?
In /dev/mtdblock2 exist a section with a RSA private key (found with Hexeditor). But it looks like that this key is the same on all devices. Because /dev/mtdblock2 differs only in the device name (J-PRS-650 <=> PRS-650) and not in the key area. I did`t understand that because I imagine that this are device unic information.
Best regards from Japan,