Well I went yesterday and tried one more thing: tried pushing the latch by hand (while the door open) into lock position and fooled it as if the door is closed; then put it into "self-clean cycle" again. I could hear the latch gear moving and it showed "locked" on the control panel. Then I canceled it shortly after and it apparently did the trick and solved the problem. My friend thanked me a lot for saving him a couple of hundred dollars. My advice: never use that "self-clean" feature; some people think it's a dish-washer that will literally clean it whereas all it does is just make it super hot and burn all the things inside but you still have to clean it...
Sounds like he owes you a "cold one"
Life's journey is not to arrive at the grave safely in a well preserved body, but rather to skid in sideways, totally worn out, shouting "...Holy Cow....what a ride!"