Trouble with a mega 2560 R2

Hello all,

let me start out by saying I'm a total beginner to arduino use. I've begun a robotics project and we were given several mega 2560 R2 cards. After screwing around with them a bit we did some basic stuff like operating servos, etc, but one of the cards seems to not work (can't upload code). I have gone down the list of troubleshooting problems, and I'm left with only the option of the bootloader, which seems likely since on reset the LED that is supposed to blink, doesn't. I'm having some trouble installing the bootloader, both in terms of knowing which one to use and how to do it. I have an AVP ISP at my disposal ( as well as an arduino uno I could use as an ISP via a sketch, but I have very little idea what I'm doing. I thought I could hook up the AVR ISP and use the transfer bootloader option of the arduino IDE and it would work but I gett errors :

System wide configuration file is "C:\Program Files (x86)\Arduino\hardware/tools/avr/etc/avrdude.conf"

Using Port : usb Using Programmer : stk500v2 avrdude: usbdev_open(): did not find any USB device "usb"

Thanks for any help! We need 4 arduino cards for our project and the budget can't really handle buying another one.