The firmware IS for North America, hence the "NA" in the version....
You bought the router in China, yet you flashed it with the North American version? Well, that wasn't smart.
Now, in case you didn't know, the Wifi radio channels differ greatly from here in the US. Japan and China I believe go up to 14. Some laptops aren't capable of that.
I am sure there are signals that aren't even allowed there as well.
Now, you bricking your router, or causing it not to function isn't D-Link's fault. It was user error. Your option is to try and get an RMA, and explain what happened, or simply move on and buy another router. Or heck, even return it to the store you got it from.