This happened to my Tab 3 when the battery was just abot completely discharged. I was going to send it for repairs, however, I left it charging overnight, still nothing, but when I held the power button for long, like 1 or 2 minutes, suddenly the battery symbol appeared and then It was charging OK. Now, one year later, the tablet is working fine, but I am always checking that the battery is not discharged too low (under 10%).