IPAD stuck on ipad not backed up message

A friends new IPAD is stuck on the following message;

iPad not backed up/ this IPAD hasn't been backed up./backups happen when this IPAD is plugged in, locked, and connected to WiFi.

When I tap OK, nothing happens. The iPad is charged and on WiFi. There is no computer to plug it into for backing up. I cannot turn it off. The same message appears on the "slide to power off" screen.