Arduino Uno R3 Trouble

My kid brother ruined my arduino after he tried uploading the grbl hex to my arduino, now when i try to use the unit it gives me an avrdude stk 500 error, i have tried using amtels flip software with the correct 16u2 hex but still wont work. when i try to upload to it, the tx & rx lights flash and stop. amber status light stays on all the time. need help please.

When you connect it, does the computer detect the usb-serial port ? If the computer detects it, the ATmega16u2 might be okay, and you could try to burn the bootloader into the ATmega328P.

Yes it detects the uno but when i try to upload to it, flashes a few times then stops, l light goes on and stays on, gives an error and fails.

This report would have more information with "Show verbose output during compilation" enabled in File > Preferences. Arduino: 1.0.6 (Windows NT (unknown)), Board: "Arduino Uno" Binary sketch size: 1,082 bytes (of a 32,256 byte maximum)

avrdude: stk500_paged_write(): (a) protocol error, expect=0x14, resp=0x64 avrdude: stk500_cmd(): programmer is out of sync