Well after I was told by DJI Service Center in the USA, that it would be 6 weeks until they could troubleshoot and reflash my Inspire after the 1.2.1.0 firmware failed to install correctly, I went and purchased a 2nd Inspire. The 2nd bird came with firmware 16, so I had to try and install the latest firmware again. As I did exactly on my first bird, I followed all the recommended procedures and this time, the firmware completed install with success! At least I have something to fly over the next 6 weeks.
One thing I noticed after installing the 1.2.1.0 firmware on the 2nd bird, is that when flying in forward direction at relatively fast speeds, the altitude begins to drop steadily. This is with my left stick sitting completely at the center and never touching it. It is very consistent and will drop about 10 ft. over the distance of about 50 yards. I keep having to give it throttle up corrections to keep it in level flight. Has anyone else seen this or is it just the natural behavior of the Inspire 1? Everything else seems to be working great with the 2nd bird.