I repaired a mini for a friend (who bought a Reo Mini a couple of weeks ago)...someone wanted to try her mini and mashed the button so hard it stayed down and the
mod started getting hot- she pulled the battery immediately before there was damage. Anyway, after this, there a a click click and difficulty pushing the button. At first I thought it was the locking pin that possibly gotten bent...tried to slide it into the button but it's a whisker to long to be all the way into the round button (on her mini)...then I figured out the real problem- the firing pin itself - the slender piece of metal that is attached to the center post was actually bent and the firing tip was bent back towards it's body...I got some needle nose and slightly straightness everything and pulled the tip away and now it is centered and the firing point doesn't slide down past the positive button of the battery- the real reason it was getting stuck in the "on" position.