The box will most likely be stuck on the version of android it comes with, any system updates usually just fix security issues or general bugs. It might also have a older version of XMBC-kodi that already has a lot of the addons already installed (usually advertised as fully loaded) You can easily install the latest version of Kodi 15.2 from the play store or sideload the apk file.
There might also be custom roms for it but I wouldn't bother with them, the only thing I did with my Minix X8-H Plus was root it with SuperSU so I could use Ad Away, even then the only app I really use on it is Kodi.
There are loads of builds that you can install on Kodi that are complete with addons like The Beast (over 1GB in size) TheBlackBoxOsTV (smaller & the one I use) & so on.
If you want you can do a factory reset on it but that will likely leave it in the state it came in or you might lose some apps or the addons in Kodi. Enjoy the box though, I wish I had got one sooner