This kind of thing is why my policy was to disconnect the battery when at any public event like this. We did a lot of
PR visits in EMS, and there were always kids around, as well as adults (at least in number of birthdays) who would do all sorts of silly things. You can't be everywhere all the time, so I would just disconnect the battery, close the door back, and not have to worry about anything except doing a thorough check of all the switches before getting ready to crank.