Mini will not change screens.

My wife has a prob;em with her Mini. It starts up only from the Power Button on top. When she tries to go from one App to another, all it does is show a Black Screen. If you hold the Home Button down Siri ask if she can help. I think the Home Button is the problem, but I would like some thoughts on it. This is the 2nd Mini she has Killed.

Thanks,,

ghostdancertwoone@yahoo.com