Your marlin config looks good and so does the gcode you posted. I would connect a meter to the ttl pin you just configured and the ground pin on that aux2 block And confirm that you’re getting 5v with fan set to full speed(255) before you go further. Make sure you tune voltage first and then current. If you can’t wait then at least read the tuning instructions at 3dpburner.blogspot.com. I’d hate to see you burn up your diode. Good luck.