Fortunately for me, the lovely Alex Mordue guided myself and Chris through this so I might be able to offer some help! The following method doesn’t use KKMulticopter (As I found it to be an unstable, godawful mess), but instead uses BLHeli Suite which is also free and a lot easier to use.
First things first, grab the modified .Hex file ( https://gitlab.com/…/Afro-MegaBrush/afro-megabrush.hex… ).You’ll also want to download BLHeli Suite (it’s free). Your ESC needs to be powered up when plugged into the PC and you must insure that the radio connector is plugged to the USB Programmer the correct way around. Some USB Programmers also require specific drivers to communicate with your PC. A quick google search will usually find you these, I can provide links for the AFRO tool but no others.
It’s then surprisingly simple! First, you’ll want to flash your Afro ESC with the appropriate default BLHeli firmware. Do this by selecting the appropriate output at the bottom left (In my case COM 3), and clicking “Flash BLHeli”. You’ll then want to select the appropriate ESC from the list that comes up. Make sure you select the correct version, eg: don’t use tail if its a multirotor esc, or it’ll go wrong.
Next, you want to click “Flash Other”. Find the .Hex file you’ve downloaded and select that. Tell the program to flash it, and boom! You’re good to go! Now, bear in mind that you may need to do some zeroing of the ESC once you connect it to the radio. In my robot, Concrete Donkey, I have to fiddle with the trim to get this right but I never centred it properly so hey ho.