To flash the firmware of Scishion V88 TV Box and V88 mini TV Box, both use Rockchip RK3229, there are basically two main methods. The first one is to prepare a microSD card with the desired firmware using a utility such that when the TV Box starts from a recovery mode, it will boot from the microSD card. Another method is to connect the TV Box to a computer and flash the firmware from the connected computer. Details follow.
First of all, locate the desired version of firmware that you want to apply to the TV Box. Many versions can be found in the web without much difficulty. Then install the USB driver designed for Android devices with Rocketchip. Open Android Tool and point to the firmware just downloaded. Without connecting to the AC power, use a pin to poke and hold the reset button; connect a male-to-male USB cable from the computer to the TV box while the reset button is being pushed and held. Android Tool should then recognize the TV Box and start the upgrading process.
Note that there is only one USB port on the TV Box that will work. For V88 TV Box, this is the one at the back of the unit. For V88 mini TV Box, this is the third USB port closest to the back. A sound should be played if the computer recognizes a device is being connected to it. (Click here to download the necessary tools mentioned in this post and a version of firmware based on Android 5.1)