Download Android Oreo 8.1 stock firmware for T9 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.
Archive size: 773 MB
Model: T9 TV Box
Platform: Rockchip RK3328 / RK322H
Image name: tvbox_l-8723-v81213.img
FW version: 8.0.00
Boot version: 2.46
Inside archive: firmware + Flash Tool_v1.6 + Rockchip-drivers-utility
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.