Download latest Android KitKat 4.4.2 stock firmware for Amlogic S805 TV Boxes from here or here. Flash it using AMLogic USB Burning Tool v2.0.0.140306_Alpha like in this tutorial.
Archive: s85_106k4_0912.rar
Image file name: s85_106k4_0912.img
Model: Amlogic S805 TV Boxes
Firmware: Android KitKat 4.4.2 stock firmware
Image file size: 347 MB
Platform: Amlogic S805Firmware: Android KitKat 4.4.2 stock firmware
Image file size: 347 MB