Download Android 8.1 stock firmware for HK1 Mini TV Box from here or here. Download previous firmware from here. Download Rockchip Driver Assistant v4.4 from here and download Rockchip Batch Tool v1.8 from here.
Model: HK1 Mini TV Box
Image file size: 913 MB
Platform: Rockchip RK3229 / RK322A
Image name: RK3229_HK1_MINI_SSV6051_9_20190418.2118.img
FW version: 8.0.00
Boot version: 2.54
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.