I got a 3D printed cootie from a friend and wanted to test it on my QCX Mini after I had used it a bit on my main rig. By mistake I did plug it into the PTT plug, not as I should have done into the Paddle plug. I powered on and moved the paddle and Bang!! I smelled amperes after I heard a suspicious click in the box. The display went bars. What happened? First and foremost, my mistake to choose the wrong plug for the jack of the cootie. Second, on the cootie stereo jack the tip and the ring are connected together. The result is a perfect shortcut of the +5V bus the ground via the cootie contact.
I have not yet assessed the full damage to the board. It is a Gen 1 version so I guess the voltage regulator is now a solid shortcut.
AA0JR Jakob