You should use a USB to micro sd card reader for your regular computer. Download and write image to sd card.
The instructions posted are for using a Tiny Core computer, as I don't have or use Windows.
No need to break open the mk802, just very carefully insert the micro sd card into the open slot, it should feel springy and then click into place.
Then connect cables to mk802 and finally apply power.
The Android image is not distrubed. It remains totally untouched. With sd card in slot you will boot to Core, take out the sd card and you will boot to Android.