Do you mean back to Android? We never sold the Venz with Android firmware and I can't find a link for it anywhere online. You could try contacting Venz via their website or facebook: http://venztech.com/ https://www.facebook.com/venztech/
OpenELEC can be reinstalled according to the instructions in this thread: http://www.futeko.com/newforum/index.php?topic=511.0