Dear Support Engineers,
I think my Uno, which I bought from you on Sept 9, just fried itself. I was running the Arduino off a 12-V regulated power supply to control a unipolar stepper motor, and it was working fine for 10 minutes, then and all of the sudden, the board stopped working and I smelled burning metal. I removed the power supply and the underside of the Arduino between the USB and external inputs was smoking hot. Now when I power the board, all the LEDs light up and the unit does not respond, either to the reset button or via USB with the Arduino program. In particular, the TX and RX LEDs light up but only at half brightness, and stay lit no matter what I do.
I have been switching from using a 5V and 12V motor, and so I had a wire connected to the Vin that wasn't attached to anything, and the only thing I can think of is that my arm might have brushed it and it came into contact with one of the other wires providing power to my project, meaning that both 5V and 12V were providing current.
The Uno is certainly fried. I don't know whether I caused it or not. I also don't know if there is any sort of warranty period for the unit or from you, and what it covers.