Hi atomriot,
avrdude: stk500_getsync(): not in sync: resp=0x00
avrdude: stk500_disable(): protocol error, expect=0x14, resp=0x51
1.Please check if the UartSB is connect well.
2.Please check the RST LED on Rainbowduino is flashing when upgrade sketch.
3.If above 2 points are correct I think should rebootloder the atmega168.
Any problem welcome
Thanks
Albert