The unanswered question is why does your original post detail a towing prep. process that is quite different than is shown in the owner's manual for your car?
The following is copied straight from the 2010 Fit manual, available online.
2. Start the engine.
3. Press on the brake pedal. Move
the shift lever through all its
positions.
4. Shift to the D position and hold for
5 seconds, then to N. Let the
engine run for 3 minutes, then turn
it off.
Severe transmission damage will occur
if the vehicle is shifted from reverse to
neutral and then towed with the drive
wheels on the ground.
If you are, as you describe, sitting in the car for four minutes, as you stand on the brake pedal, with the car in drive, you just might have answered your own question as to why the trans. grenaded. The steps are there to send a message to the computer that the thing is going to be towed. Just like the grave warnings to not go from reverse to N, I would suspect that holding the thing in drive for four minutes, instead of the required five seconds, probably isn't the greatest idea, and may be exactly why the thing failed.