Download Android 7.1.2 firmware for MXR Pro TV Box from here, 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: MXR PRO 20180319
Model: MXR Pro 4GB / 32GB TV Box
Image file size: 793 MB
Platform: Rockchip RK3328 / RK322H
SDK version: RK30_ANDROID7.1.2-SDK-v1.00.00
FW version: 7.1.00
Boot version: 2.44
Model number: MXR PRO
Build number: rk3328_box-userdebug 7.1.2 NHG47K eng.user.20180319.225151 test-keys
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.