Here is the stock firmware for Tronsmart MK808II tv stick.
Tronsmart MK808II is the upgrade version of MK808, it built in external antenna, has better wifi signals, and use better flash ic, have better sd card write/read speed. also tronsmart put a new TV Launcher on this model.
Here we go, firmware download link is:
The Upgrade method is the same as all rk3066 base tv sticks. and if you met the driver problem, you can read this instruction: