During the weekend I managed to capture the UART traffic used by the FVT USB Link software to upload the latest firmware revision 170818 to the Favourite 120A 12S ESC (also known as Maytech MTES 120A SBEC) and noticed a
#Skywalker20A# string in the byte sequence right at the end of the firmware upload:
With a bit more work I managed to figure out that their
HGM firmware files have all bytes XORed with
0x68. And with that I could decode the full firmware and notice multiple references to the BLHeli firmware.
Here is the full write-up on how I did that: