Hello! So i performed the loopback test..as you said when I wrote something in the Serial port and pressed enter it appeared right away in the port..does that mean that the communication from the pc to the board through USB cable is ok?
When i tried to upload something to the board again the same problem..now it is stuck with the last code that had been uploaded before the error!
I guess now i have to try burning the bootloader..should i follow the official instructions from arduino site? if i perform it is there any chance i also destroy my second Arduino?