I’m assuming you’re testing by printing wp_query directly with the PHP code I gave you, rather than trying to use MapPress, is that correct?
You combined the two queries correctly and they looked fine to me.
Of course, the combined query would only return events that are in the given categories AND have end_date < 20130618. Have you checked that you have posts that meet ALL of those criteria? Or are you instead trying to get the results for events in the given categories OR end_date < 20130618?