Huh, if my reset is OK, I can't possibly figure out where my circuit is going wrong. I connected an LED to the proper pin and it blinks a pattern just like it's supposed to according to the Mightycore bootloader documentation. Can it be something related to building it on a protoboard and not a PCB? I didn't clean my flux, but as far as I know the one I use is not conductive and I don't see any shorts.