When Charge My Kindle It Flashes On And Off And Connects, Unconnects No Charge

When I turn on my kindle the screen flashes several times before finally turning on. Then I try to plug it in to the usb port to charge it and it connects and then goes away and repeats this five or six times before it finally stays connected. I plugged it in for six hours yesterday it said it was charged. I read for about an hour turned it off and when I turned it back on it had the lightening bolt on the battery indicator like it was charging and it had been unplugged from the computer for two hours. this morning it was dead. do i need to exchange it for a different one? I have the 79.00 version not sure which one if Kindle one, two or DX it was a gift from Target.