Download latest Android KitKat 4.4 for MINIX Neo X6 Mini TV Box from here or from here. Flash it using AMLogic USB Burning Tool v2.0.0.140306_Alpha like in this tutorial. Download previous version from here.
Archive name: X6_S805-201410241144
Archive file size: 395 MB
Update file name: aml_upgrade_package.img
Platform: Amlogic S805
Platform: Amlogic S805