Download latest Android 7.1.2 stock firmware for Sunvell T95Z Plus TV Box from here or here. Here you can read about the unboxing Sunvell T95Z Plus Android TV Box. Download previous firmware from here.
Archive: T95Z Plus firmware+Tool+Flash instruction
Model: Sunvell T95Z Plus TV Box
Image file size: 556 MB
Platform: Amlogic S912
Image name: aml_upgrade_package.img
Inside archive: firmware + Amlogic S912 burnning tool (setup_v18.104.22.168_build7.exe) + Instruction
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.