My bet is on that crappy universal charger. When I had my D2, the stock charger broke and I bought a cheap charger for it that worked fine. I decided to try it on my Gnex and it does not charge it.
I can also confirm that not all universal chargers are truly universal. My one friend had a universal charger for his phone, forget what he had, but it would not charge my DX, though the charger fit. Might want to go pick up a GN charger or find someone who has one to find out if a stock charger works.