I purchased one of these a few weeks ago:  http://www.sparkfun.com/products/760
I've been trying to update the backpack for it to version5 through avrdude, but I keep getting this error after it confirms the baud rate:
avrdude: stk500_recv(): programmer is not responding
The serial port is correct and so is the board select (Mega2560)
This is what I've been entering in terminal (yes, Mac):
avrdude -P /dev/cu.usbmodemfd121 -b 19200 -c avrisp -p m2560 -F -v -e -U flash:w:RGB_Backpack_v5.hex
Can someone please help me?