Download Android Lollipop 5.1.1 stock firmware for Rupa Mini AX5 TV Box from here or from here. BTW, you can now buy Rupa Mini M5X TV Box from Gearbest for only $51.63 with free shipping world wide.
Image: update_rk3229_ssv6051_minimx9_rupa_20161207(MINI A5X).img
Model： Rupa Mini M5X TV Box
Image file size: 543 MB
Platform: Rockchip RK31229 / RK322A
Model number: MINI A5X
Boot version: 2.31
FW version: 5.0.00
Build number: rk322x_box-userdebug 5.1.1 LMY49F eng.foxluo.20161207.185840 test-keys
SDK version: RK30_ANDROID5.1.1-SDK-v1.00.00
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.