Installed update, now ZenPad won´t boot up.

My daughter was prompted to update her software. She did this and now cannot do anything on her ZenPad. We have tried to restart the device a number of times, but each time, it switches on, shows the Asus logo and then the circle that shows it is ´thinking´ or processing something.

I need to get back into this device but can´t even get a start screen.