I decided to update FC and Navi from V2.02 to V2.06. The update was accomplished separately for the 2.2 FC and the Navi. All appeared OK. Parameters in MK Tools were adjusted to match what I had in V2.02. When the copter start was attempted (after gyro cal), there was no start. The OSD would start and display correctly for only a few seconds. After which, it would cycle through the "Smart OSD" logo, video with no OSD and brief flashes of OSD. Meanwhile the MX-20 was beeping with a rising three-tone dah-dah-dah. I cannot find the meaning of these tones and cannot find any indications of trouble. Do any of you know what the trouble is? I chose to revert to V2.02 (MK Tools, FC and Navi) and I was back where I started. It had been a vexing adventure. The copter behaved normally in all respects once back to V2.02.