this is a manual how to upgrade your Android TV Box RK2918 with 4x USB looking like this with a rooted Firmware:
There are some versions of this Box in blue and black color as well as with and without android tv logo. Important is that you have the Box with 4x USB (NOT 2x or 3x USB).
I rooted my 4x USB RK2918 Android TV Box. Upgrading the Box is just a few steps away:
1) Download Firmware from Uploaded.to
EDIT 2012-03-04, added new mirror: https://rapidshare.com/files/3368714344/update.img
2) Copy update.img on SD Card root folder, insert SD Card into Box
3) Start Box and wait for upgrade dialog, confirm update
4) Wait while Box restarts and update performs
5) You're finished and have a fully rooted box
Content of Firmware
-Made from original firmware, Android 2.3.1
-Removed default homescreen, replaced by ADW Launcher (regular phone homescreen)
-Added Superuser + full root
-Removed Youtube App (old non working version, can be replaced by new one)
-Full support of upgrading via SD Card, like in the origin firmware
I got some root apps like droid VNC server running well.
Enjoy the freedom and homescreen of this rooted firmware.
Disclaimer: I am not responsible for any damages resulting in this upgrade. I tested with my box and everthing works fine, as it is made from origin firmware. You may loose your warranty if you do the steps above.