Download latest Android KitKat 4.4.2 firmware for MK809III with Ap6330 WiFi chipset from here or from here. Download previous firmware version from here. For MK809III with 8723 WiFi chipset download firmware from here.
Firmware: TV3Q_RK3188_AP6330_Android4.2.2_20140423
Model: MK809III with Ap6330 WiFi chipset
Image file size: 274 MB
Platform: Rockchip RK3188