Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I'm frankly not sure how to interpret what you are asking about. May I offer all of my thoughts on the case thus far?:
1: Either, the initial less-than-maximal charge was slightly damaging, or
2: the tablet is simply defective from the vendor or store, and it was in no way your fault at all that it has, apparently, failed.
I really am not sure which is the case, but as far as practical considerations are concerned, you should
A: examine the charging system, for anything old, weak, or dirtied (enough to obstruct charging.)
B: consider whether *any* light, etc., is appearing on the screen, or at least a power/charging light is lit, after another 6 hours of *continuous* charging with the newest charging cord and adapter available.
If the charging system is new and clean (esp. the jacks/plugs and their metal contacts) and the cables are new and unstressed, and you also get no signs of life whatever after another 6 hours *continuous* charging, and after that the tablet fails to turn On even briefly when you attempt to start it up... then you have a defective tablet, from the vendor or store, quite evidently, and should pack it up and return it for an exchange (for an equal or equivalent tablet) or a refund.
(If it comes to its being a failed tablet, I advise packing it up and returning it very promptly. The return/exchange arrangement expires quite soon after purchase - the exact term of time being dependent upon the vendor or store. But it is usually short, at most 2 weeks, sometimes only 1 week, after purchase date.)
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The battery may have failed. China manufacture is cheaper, sometimes, for a very rational reason: the quality control is hastier and poorer. I could tell you tales... but no matter.
The thing is: try what I advised for another 6 hours. That is most likely to be remedial to the system.
If it stays dead after that, it *is* dead. (But, just in case, be sure to fully charge up, before first use, any tablet you get, hereafter.)
How are you using the original charger, and the travel adapter?
Ideally, you would use the original charger, and *not* use the travel adapter. Travel adapters are for other voltage levels. Using it wrongly could result in damage to your tablet, yes.
But, have you used the travel adapter yet at all? if not at all, it was rightly done to have avoided use of it until you were in a foreign country.
I see. So did you set the travel adapter correctly from the first?
Remember, when considering that, the way the tablet did indeed charge up to (as you have said) 28 %. That is a sign that the initial configuration was the right configuration.
*If* it had been wrong, your tablet would have blown out immediately!
Did you change that configuration, since then?
A USB port is a USB port. Their voltage is according to a standard: 5 Volts, period.
So the USB port charging attempt didn't harm it - if the source was USB also.
I think it's pretty sure it was simply a defective tablet (probably, a battery that went kaput even before fully put into use.) Return it with an easy conscience, essentially. Get another one, charge it up fully at the first charge, see how long it lasts.