I have a problem with my Arduino Uno rev3, which suddenly started to overheat near the small, black, square element next to the circular cable power input port, isn't recognized by Windows 10 (I have the drivers installed, it was working just a while before it broke) and, what is strange, the internal diode (labeled L, next to the digital port 13) is always on. The PC doesn't even notice that any device is plugged in, the arduino IDE doesn't see any active COM ports (the menu option is grayed). The usb cable supports data transfer and is not broken. The arduino was working a while before, I have the drivers and I tried restarting the PC. Now I cannot upload any program to it, neither can I flash the bootloader. What can be wrong and is it possible to fix it?

  • The ATMega16U2 that does USB is either broken or not receiving power. That little black square is a regulator and it shouldn't get too hot, so there is a short somewhere. What were you doing with your Arduino before this happened? – Los Frijoles Mar 4 '17 at 17:06
  • It was plugged to a 12V power source and I believe it got fried, I was changing the circuit. Is there any test to find out what is the problem (like the loopback test, which I cannot pass, as the arduino is not seen in the Ide, neither in the serial)? – artus90 Mar 4 '17 at 17:09
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    Unfortunately without substantial experience and the tools to do surface mount rework, the issue will probably not be correctable even if it could be identified. You'll likely need to get another, and be more careful when connecting it to external supplies. Perhaps your 12v supply is not always and exactly what it claims to be. – Chris Stratton Mar 4 '17 at 17:22
  • Right, thanks. Is there any chance that the seller/the producer will take it for a warranty repair? – artus90 Mar 4 '17 at 17:39
  • Likely not. Though I don't think your 12V plug is a problem; the regulator is rated up to 20V input. What do you mean when you say changing the circuit? Where you plugging stuff into or changing wires on the arduino with it turned on? I generally avoid doing any kind of stuff like that on energized circuits because you never know what two wires you might accidentally touch together. – Los Frijoles Mar 4 '17 at 17:40

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