Thanks for reply kartu, let me describe this more detailed.
First, I found the information about chinese hacked firmware here:
The way to make this firmware is, unpack the hacked russian firmware, replace the font files by fonts with chinese font support and change the menu words, then repack it and flash. Same way to make the russian firmware.
So I download this firmware and try it out. It worked but the font and menu language is not satisfied by me. So I try to make a customed firmware by the very same way to make the chinese hacked firmware I downloaded.
But my firmware is not successful. After flashed PRS-600 keep restarting. I can fix this by flash the firast chinese hacked firmware again. So I posted here to ask if anyone know what make PRS-600 keep restarting or what's go wrong in my process. If the firmware I downloaded worked, no reason mine can't...I think so.:P
I know there are always danger to hack any device. but there are so many people successed on this so I wish to make a try.