Without opening to see, could be ANYTHING. If it's completely not responding, might be something as simple as battery connector failed. Is it Lipo batteries? 18650 batteries? Self built? Name brand?
If it's a clone, it's probably going to be easiest to simply replace. If it's a name brand box, the vendor will probably work with you. If it's a self built, pop it open and check your work.
I'll say this, I've not read any review of the chdna30 clones being positive. Most seem to have issues of some kind or another....before anyone attacks me, I have no issue with clones in general, just poor quality, which most of the reviews seen to indicate....

either way, it sounds like a bummer dude and I feel for ya.... I'm sure with a little more detail we can determine the problem.