Actually, what others brought up about the ignition SWITCH and the very common, + and negative cable ENDS being the source of your problem, should be your first chk. point. If you don't really know if the battery is discharged or not, simply try a known good battery from a good car as a inexpensive test.
Had a customers no-crank about a month ago, and it turned out to be the Ground cable end, but at the engine block,(dirty,high resistance). Battery did go flat however first. Remember,there are 2 ends to each of the battery cables to clean and or tighten.
High resistance, on the Ignition switch contacts or cable ends, it doesn't matter which, they will both drive your electronics crazy... Tom