I don't want to be boring, but if you hooked a 5 volt device on your DUE, you probably killed your board, yes. 
Next time get a few of those, they are really not expensive and they protect your stuff.
Or these if you want breadboard version:
I will study you code and give you news about it later... But, the most important thing is, trust the instruction that you find on the Arduino website, they are there to help you. 
If it's says not to hook 5volt, there is a good reason for that.