Buyer beware. I have a working nano from gravitech, but ordered an "Arduinno nano 3.0" from amazon. After a few weeks, it arrived from shenzheng, china. It ran a few sketches, but after an hour it no longer worked. Multimeter showed only 0.015v on Vin? (running from USB), and initially 5v (pin 27) showed 4.8v, but now it shows only 2.6v and the USB is no longer recognized by PC. sigh. you get what you pay for.
Others I see have complained about Amazon selling units as Arduino, when they are in fact clones.
Return it to Amazon.. If you have powered it properly and used it properly then it is defective, Have you had it for more than 30 days?.
If not Amazon is Always good about returns... I have purchased local stock from SainSmart, sold by Amazon that failed. 3.2" 320 X 240 displays.
I bought one that was bad out of the box, I emailed them and got a RMA that day and shipped back the part.. Free too.
Bob
Well...as you've discovered yourself, you get what you pay for.
If you need a well made small Ardino compatible board I'd strongly suggest you check out the Teensy boards. All US made. Excellent support.
Even then smallest one is better than a Nano and at $16 priced very competitively. Not to speak about the newest Arm based Teensy 3, which is also Ardino compatible and vastly more performance than a nano.
http://www.pjrc.com/teensy/