Here is the instruction for how to root your tronsmart vega S89 and Vega S89 Elite quad core tv box:
1 Power on your Tronsmart vega s89 tv box. and turn on the USB Debug choice under setting;
2 Use the usb cable to connect your tronsmart vega s89 tv box with your windows PC(now only support root under windows system)
3 windows pc will detect to find a new device, and try to install the drivers, if you have problem to install the driver,please make sure to install the following tool in your pc:
4 Now we need to download the root tool, here is the download link:
install the “VROOT” and run it, it will detect the tronsmart vega s89, and just click “get root” button. This tool will help you to gain the root.
5 After one restart of your tronsmart vega s89, the vroot will inform you that you already get root access.
I think this method should work with all of the amlogic s802 base android tv box, i will test with other model, and report.