Tablet was working fine. Now it just flashes

My tablet was working fine. I used it this morning but this afternoon found it flashing the Dragon Touch Powered by Android logo but not progressing beyond that.
I have tried to re set pushing the on off button and holding. It vibrates as if it's going to go to start up but then just keep flashing three second with the logo six seconds off.
I've tried holding down the volume buttons and the on off key? It is fully charged.
What can I do?