Download KitKat 4.4.2 stock firmware for Beelink X2 TV Box from here, here or from here. Download previous firmware from here. Flash it from PC using LiveSuit v1.11 or from SD card using PhoenixCard v3.09.
Archive name: update_XII_v207k4
Archive file size: 373 MB
Platform: Allwinner H3
Build number: 4.4.2 KOT49H 20160326 test-keys
FW version: Homlet4.4.2-Qin2-v1.0release
How to install
● The first update method is USB fastboot (the USB cable is must be A-type): Install the update_XII_v207k4.img via Phonixsuit.
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.