Why is my tablet flashing on and off at the start

My tablet has been on change and I've tried turning it on, but it seems to be flashing every 8 seconds the screen when you turn on 'acer, powered by android' PLEASE HELP ME im not sure what acer iconia it is...but that's what its doing, if someone knowns what to do, or has had this experience and has solved it please answer and help, thankyou