The tablet you purchased is a commercial grade data entry terminal for the Chinese market. The tablet isn't intended to be sold to consumers but corporations with an IT department. The IT department would receive firmware updates directly from the manufacturer for installation on the tablet. That is why there is no website and no firmware download for you.
I just wanna say thank you for your explanation concerning that a31s ma80505_v14_2014010800 because i have try to find firmware of that tablet but i couldn't. Is it possible to install android os in this tablet?