Just got my P2 and haven't had a chance to get it out yet but hope to today or tomorrow. To be clear, S1 is for compass calibration only, right? Just keep S2 in GPS and fly away? I plugged my P2 and opened the DJI Assistant 4.0 iOSD software....says 4.0 is latest but says no device under firmware when I click "no updates". Am I missing something?