Phoenixset:
Hey, i know this may be late but i had same problem, try this if it's not too late:
in arduino IDE goto: Tools->Processor and choose ATmega328P (Old BootLoader).
That worked to me, no need to reflash it.
Now you can upload any sketch.
In 2017 when this thread started, the 'old bootloader' option did not exist; only came in the beginning of 2018 with board manager 1.6.21.