"But still there's no way to tell what version you have even if there are multiple version which I doubt."
Part of my job is dealing with firmware. In the old days (not that long ago), I was the guy that "burnt" the newer version of firmware into EPROMs. Now, I use a laptop to "flash" firmware (EEPROMs, FDIMMs, etc).
There's always a way to tell the version, even if it's something as simple as a label on an EPROM. Other times, there's a service mode that you get into with a weird combination of buttons pushed...