Why is my tablet keep randomly turning off

My tablet keeps going dead randomly. I charge it to 100%. It will go til it just doesn't want to go and die,at random amounts of charge. It won't turn on again til I, put it back on charger and then it will turn on straight away. Had similar problem recently with it when it would die at specific amount of charge. Ended up changing battery and it worked fine,for,a couple of weeks now this.