Sorry to hear. I don't know how it's a scam...there isn't necessarily a return policy in China. That's the risk of doing business on ebay.
Is it completely dead or are the lights flashing? If flashing, try to reset.
That being said, most dash cams are of poor quality. They are not used here much yet and the locations which they are used in are sketchy at best. Chinese and Russians do not have as high of a QC system as Japan/NA obviously.
Take a look at the blackvue line:
http://www.blackboxmycar.com/
Expensive, but high quality.