This funny console was given to me as a gift and I've spent more time figuring out the hardware and what it can do than I have playing actual games on it. Disclaimer: I've used a linux machine to do all my editing/customizing, some of these things likely won't work the same (or at all) on other OSs.
I've heard many reports of the SD cards that these consoles come with being unreliable, so one of my first orders of business was to make a clone of it on a higher quality SD (not the highest quality, but with at least one with a brand name, in my case). I created an ISO image of the original SD (this took a while), swapped to the new SD card and copied the backup image onto it.
sudo dd if=/dev/sda of=~/k36-backup.img bs=4M status=progress
sudo dd if=~/k36-backup.img of=/dev/sda bs=4M status=progress