I’m using Mission Planner, and every time I want to fly, I’m forced to re-calibrate the APM 2.6 (all 15 steps). After each flight (well, crash), I disconnect the battery that powers my motors, ESCs, and APM. Is there a certain way to power off the APM so I’m not forced to go through Mission Planner before every flight? This is especially important to me, because it often takes several attempts to connect through Mission Planner. I’m appreciative of any help 
Looking for a follow up to this question. I to am having the same issues. My main issues isn’t so much connection - its the length of the cord to connect the quad to my mac. Its terribly short but after 3 attempts at connecting with a longer cord (3", 6" & 9" lengths) I found that only the 3" cord supplied the necessary voltage.
I too do not want to have to re calibrate after each flight. Is there not a simpler way?!