i have another arduino Uno i uploaded arduinoISP sketch connected atmega16u2 ICSP header to the programmer used WinAvr and i write the firmware using this command
avrdude -p m16u2 -F -P COM12 -c avrisp -U flash:w:Arduino-usbserial-atmega16u2-Uno-Rev3.hex -U lfuse:w:0xFF:m -U hfuse:w:0xD9:m -U efuse:w:0xF4:m -U lock:w:0x0F:m -b 19200
and everything went smooth the new firmware was written , now i tried to connect the uno again but nothing happens no hardware detected
obviously the atmega16u2 chip is not fried there is still hope ....
if anyone could help me i suspect one of the components needs to be replaced a capacitor a transistor etc ....
any tips or advice will be much appreciated
thank you all