The ultimate resolution of getting the MK802 back to normal from software issues is to do the firmware recovery. The following is the steps:
Tools You need
PhoenixCard 3.06 program
img file (Latest firmware as of 20121208)
micro USB card (mini 2GB)
SD Card Reader
micro USB card (TF-card)
In the Windows
1. Plug the USB card reader with the micro USB card into Windows 7
2. Run the PhoenixCard
3. Select the drive with the card reader
4. Select the img file.
5. Choose the Write mode to "Product"
6. Click "Burn" button (which will be enable after you choose both the drive and img file)
7. Finish burning the img file into the microSD card. (there are progress showing in the program)
In the Mini PC MK802 II
1. Unplug the USB power first.
2. Plugin the microSD card.
3. Plugin the USB power.
4. The light will be on.
5. Wait for 5 mins until the light is off. (there is no screen output)
6. Unplug the USB power and the microSD card. (Remember)
7. Plugin the USB power then you will see the Android Logo in the HDMI output.