Download latest Android KitKat 4.4.2 stock firmware for MK808B Plus TV Stick from here or from here. Download previous firmware from here. Download a newer firmware from here.
Archive name: H mk808b plus pc upgrade
Image: H mk808b plus / huakewei_s805_mk808b_rtl8723_20150618.img
Archive size: 1,04 GB
Model: MK808B Plus TV Stick
Platform: AMLogic S805
Caution: Please do not update firmware unless you know what you are doing, you really want it or it is absolutely necessary. Firmware updates may occasionally have bad results, like bricking your device, temporarily or permanently. The firmware update process is done entirely at your own risk. Before attempting to update the firmware, back up your data.