The scariest moment is when your Canon printer had paper jammed and you tried to remove it but suddenly the machine start to move by itself.
Do you know, when we accidentally move one of the machine part, it can cause error?
So, in this situation you need to stop remove the paper too until the machine stop.
In this video, this is the situation where I remove paper jammed halfway (link: ) If you’re not sure how to do it, better just bring your printer to the nearest Canon service center.