Hello,
I bought a second hand armattan chameleon, with betaflight version omnibusF4 3.1.7 Apr 3 2017. Connection with transmitter worked fine, I even did a little test flight.
Now, like I thought I was supposed to do, I changed the version into the latest version. After that, my transmitter could not connect any more with the drone.
So, it took me a while, but I managed to find a hex file with version OMNIBUSF4 3.1.7 May 16 2017. I had connection with the tranmitter again!!! 
After changing the modes and ajusting the buttons , I went for another test in the field. A little throttle up and...drone was freaking out! No airmode on.
So, what now? Should I try different betaflight versions again, and to start with, should I try the apr 3 2017 version???
Any idea where I can find this version? In Betaflight configurator, the oldest version is 4.0.1 for may 2019.
