He was renovating a school, thus he was carrying around a screwdriver (and probably lots of other tools) and possibly popping off outlet plates left and right

He was renovating a school, thus he was carrying around a screwdriver (and probably lots of other tools) and possibly popping off outlet plates left and right (in preparation for, say, painting the walls). If I found an sd card with encrypted files I'd be curious as hell. Maybe the guy who hid it got the idea from Breaking Bad.