What is ERROR 2009?

My Iphone 7 suddenly only shows a black screen. For a long time, we kept trying to turn off the iphone but it would not respond. Pressing the button on the right side of the iphone only makes the screen go black or totally off. When I tried to connect it to itunes and chose UPDATE the iphone, it now shows an apple LOGO for at least the last 15 minutes and a message came out on the computer "unknown Error (2009).

Please help me what I can do.