Arduino uno board not detected when connected via USB no matter what OS I was working with Arduino in Win 8.1, when suddenly it stopped work. I tried to reinstall the drivers and IDE several times, but it didn't solved. 

In Win 8.1, when I plug the arduino, I get the pop up message:

USB Device Not Recognized in Windows

Also, when I try to upload a sketch, I get this error in Arduino IDE:

avrdude: ser_open(): can't open device "\\.\com5": the system cannot find the file specified


I switched to Linux (Debian Jessie 64 bits), but it also doesn't get recognized, and I getting the same error, only the port Is different.

I am guessing is a problem with avr, but I don't know what can I do about it. 

Other  symptoms:


In both systems the port tool in IDE is grey, so I can't choose a port.
When I press the reset button in Arduino, nothing happens.
The led L (13) is constantly shinning. It never blinks or stops.


Solutions I tried:


Reinstall drivers
Modify the preferences.txt file to change the COM port
Fall back to a previous IDE version
Change the usb cable
If the port selector in the IDE is greyed out, and the OS is throwing an error, it's likely the Board is damaged. Either The firmware on the serial device or the chip is fried somehow. What's happening is that the usb part is failing, so the Com port part never works.