Titillating :
How do you know it has a full charge if it won't turn on?
It'd help if you could elaborate on the issue. Did this happen suddenly? Were there any circumstances that might have caused this? Did you recently update any apps or software?
Sorry for the lack of info, I'm just exhausted w/this and most of the answers when this question was already asked were silly, not all just most. Okay, so I had it plugged in to my laptop(USB) which I've always done, no problem, when a small alert came on in the corner of my laptop (Alienware) and said something I couldn't read quick enough, then it disappeared. I couldn't find the alert anywhere to read it. Then my phone went dead. I turned it on, it acted fine, the battery finished charging like normal so I took it off, and it went dead as doornail. I tried repeatedly to start it up, no luck. I plugged it back in and tried and it worked-for a few seconds-then dead. This is the pattern. Unplugged: nothing; plugged-in: sometimes will start, but only for a few seconds. I tried changing the battery to no avail.