This happened to me as well, just 3rd cell was blinking. Once I've contacted dealer - they advised to send battery back (although I asked if it might be charger problem...). After few tries and several hrs of charging I really damaged the battery, because 3rd cell had 1.8 Volts or something. I sent battery back and purchased another one - it had the same result and 3rd cell started decreasing volts, which was clear indication that Charger was bad, so I've sent it back.
Meanwhile i purchased IMAX B6 charger from Hobbyking and all 4 batteries are charged OK.
My question is why Turnigy Nano 2200 battery gets back ~2100 mAh although I land immediately after seeing red light on Phantom and voltage is around 3.7 of each cell? It's 96% and much more than expected 80% to save the battery - any ideas?