Download Android Oreo 8.1 stock firmware for A5X Plus Mini TV Box from here, here or here. Download Android Nougat 7.1.1 stock firmware for A5X Plus Mini TV Box from here. Download previous firmware from here. Download Rockchip Driver Assistant v4.4 from here and download Rockchip Batch Tool v1.8 from here.
Archive: A5X Plus_20180515_r1
Model: A5X Plus Mini TV Box
Image file size: 698 MB
Platform: Rockchip RK3328 / RK322H
Firmware version: 8.0.00
Boot version: 2.46
Model number: MiniA5X_Plus
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.