My phone was working perfectly fine the night before and then randomly wouldn't hold a charge, it kept charging on and off I even tried different chargers. And then it wouldn't charge at all. A few hours later it started charging fine with a different charger and the battery even lasted a lot longer than usual. The next time i tried to charge it, it wouldn't charge at all and still won't! Is the battery completely gone or is it a issue that can be fixed?