If you were just topping off the oil (say, .25 quart, maybe) then no, that wouldn't damage anything. Now if you added 4 quarts or so you may have a problem.
If it was all good, then went south and all you did was add oil and nose around some electrical connections, then I'd bank on something electrical failing: whether it be bad wires or a sensor that gave out coincidentally at the same time.
I'm still trying to figure out what it was you found near the battery that wasn't connected to anything.
