You just never want to see this message:
Uh, this looks fake but, alas, it’s our iPad today after 3-year-old tried (repeatedly) to unlock. Ideas? pic.twitter.com/5i7ZBxx9rW— Evan Osnos (@eosnos) April 6, 2019
Helpfully, as Glenn Fleishman points out, there’s this article from Josh Centers and TidBITS which lays out various fixes. Key to them all is making sure there’s a backup if you want to actually recover the data on your iOS device.