When I connected an external power supply to my Arduino Uno R3 (it was connected to PC via USB cable too), I heard Windows disconnected device sound and the device isn't visible since then (nothing happens when I plugin the USB). Cable is ok, because it works with the second Arduino. TX/RX LEDs don't blink anymore.
Following this guide, I checked two things:
- I was able to flash ATMEGA328 with LED blinking program using external ICSP programmer and it worked
- I was able to flash ATMEGA16U2 with the official firmware and it completed without any error
Is there anything else I can check? I'm not really desperate to fix it - I just want to know which component is broken.