Sometimes I forget there’s a whole dang computer in the Studio Display, then I come across a link like this one:
If a warning symbol appears on your Studio Display, your display is in recovery mode and needs to be updated.
If an error occurs while updating your Studio Display, a warning symbol and support.apple.com/display/restore appear on your screen. Use the built-in display on your Mac or another display connected to your Mac to update your Studio Display.