Heard a pop sound, engine lost all power and will not turn over

Your combination of symptoms points to a broken timing belt. At the mileage you listed, it is close to the time a second replacement belt is recommended. This engine uses a number of parts including belt tension-er and idler pulleys, and one of those pulleys is the water pump. The original water pump used a plastic impeller that caused a lot of trouble. If your mechanic has your best interest at heart, he is going to want to replace all the parts as a set, and replace the water just out of principle as well as for the impeller problem. I would be leery of any shop offering to replace just the timing belt. That is a cheap fix that leaves a lot of old critical parts on the engine.