DSI will not charge, or turn on

This DSI was bought in December. Yesterday my daughter said while playing her DSI she went to plug in the charger and it would not charge. She thought it was a problem with the actual charger cord. I took a look at it and when I plugged in the charger and then plugged the cord into wall, the DSI charge light would flash on and then off, and the power button would flash on and then off. The DSI would not charge. I have been attempting to fix the problem and have gotten nowhere, using the operations manual. Then I went online to get help troubleshooting. I am not sure if the DSI needs another charger cord, even though it used to work fine. Or if the DSI's rechargeable battery in the back needs to be replaced. Could anyone please help me with some tips and/or advice?