I have bought two of theese "Rizone" players too. Both stated as 32GB, real 4GB (Samsung chip K9LBG08U0M)
SAMSUNG's Digital World
I persuated the seller to refund full price. Then he told me I can keep the pleyers and asked me to leave possitive feedback; what a fool..
Main chip is probably Action, part no. ATJ2135F. It looks like the manufacturer is Shenzen Honsin Technology Ltd.
Flash MP3 Player Manufacturer
The player there has a little amended covering, but the control buttons looks like they are in same possition. The specs also look the same.
I tried to find out more about the manufacturer to get firmware but had no luck.
Maybe someone else will have.