Guys, I made a major breakthrough today - I successfully completed my Pixhawk 6C upgrade on my Tarot 650 Sport. After weeks of frustrating problems and trying the patience of all in the community who tried to help me I got it working.
What I did was to punt and reset all parameters to their default values and go through the steps once again. Of course, I had to go through all of the calibrations, and as it turned out I also had to reprogram my transmitter (I think there was a loose battery and settings don’t persist?). After completing the calibrations, I powered up the aircraft using the onboard lipo and connected to Mission Planner via the telemetry modems - the ESC beeping stopped, I was able to arm the aircraft and successfully run the motor test! I then mounted the propellers and was able to successfully arm the aircraft outside (secured down with some ceramic tiles), and throttle up the motors - they run much more smoothly! I was successful all around.
I have to do a few more things before I take it out for a test flight. The weather here in Colorado is freezing anyway and its really windy. I hope to capture some video of the test flight and post it.
I want to give my sincere thank you to all who tried to help me. I know I tried your collective patience to extreme but in the end I had a successful outcome.