I just got my first Arduino Uno R3 4 days ago. It was working fine without any hiccups, until today. I got curious and I tried measuring the voltage between the Vcc and multiple pins with the GND with a multimeter, until the built-in LED on pin-13 suddenly turned on, and my Arduino board suddenly got very hot.
I panicked and disconnected the 12v power supply, wait for it to cool down, and decided to connect my Arduino to my PC to check if it still works, but I get the "USB not recognized" pop-up notification from windows. The board gets very hot again and the LED on pin-13 is always on. I tried uploading a sketch but I got this error message:
Arduino: 1.8.13 (Windows 10), Board: "Arduino Uno" Sketch uses 3190 bytes (9%) of program storage space. Maximum is 32256 bytes. Global variables use 247 bytes (12%) of dynamic memory, leaving 1801 bytes for local variables. Maximum is 2048 bytes. An error occurred while uploading the sketch avrdude: ser_open(): can't open device "\\.\COM3": The system cannot find the file specified.
The "Port" selection on "Tools" tab on Arduino IDE is greyed out.
Is my Arduino is officially fried and no longer usable?