Not as much a mistake, but a moment of panic over something stupid.
Was taking some shots in studio, about an hour in all of a sudden the camera stops firing. I look at the back everything is black.... That's odd... Power it off and then back on again.. Still nothing. Like there was no power. I figure I must have not charged the batteries (Although pretty sure I had)
I only have 2 of the canon batteries (both already in the grip) but have a second tray for AA batteries, so pull that out of the bottom of the bag, pop in 4 new batteries, pop the tray in... still no power.... At this point I'm slightly freaking out. I have a backup camera, but there is a big difference in them and dont want to just give up. Figure I'll try running without the grip and try one Canon battery at a time maybe one is good....
As I'm about to remove the grip, I notice it is slightly unscrewed. (2-3 millimeter gap) . Screw it tight again, pop in canon battery tray and power on... voila. Heart starts beating again. 1st time that ever happened in 2-3 years of using it. Model and I had a good laugh.