There were some confusion on what’s the minimum things to plug in to properly flash BLHeli onto the the ESC. I know I had the same questions when I started out and when you run into a problem, there are too many variables to contend with.

An overhead view of how I have mine set up. You don’t need anything more than this to properly flash the ESC.

The minimum setup to allow BLHeli flashing.

And for completeness, here is the order of how I hook things up.

  1. First, I connect the ESC to the USB Toolstick.
  2. Next, I connect the USB Toolstick to the computer.
  3. Finally I connect the battery to the ESC to power it up.

I then open up the BLHeliSuite program that user 4712 from HeliFreak wrote.

I click on the “Flash BlHeli Hex File” button. Then select the proper firmware I want to flash over and hit the “OK” button to flash the new firmware onto the ESC. (You’ll get prompted with a couple of dialog boxes warning that you’re about to overwrite the original firmware on the ESC. I just answer ok to dismiss them and continue on.)

Let me know if that helps you or if I need to clarify any steps.