What is wrong with my kindle?

[KirbyJ]

Yesterday I got a book to read on my Kindle and it started downloading but then the screen shows this

And now it won't let me close it and I can't click anywhere. I can't even get another book to read since it is frozen like this

 

[nuthatched]

Can it be turned off and on?

 

[Sally PB]

Can you force it to turn off by holding in the power button? It might take several (10? 15?) seconds. My Kindle has done some weird stuff, but not this.

 

[KirbyJ]

I can turn it off and I tried that and it is still frozen