Mi Note 10 Lite - Stuck at empty background or the orange Fastboot logo.

[wrein]

Hi, I've a problem with my mom's Note 10 lite. This morning the phone woke up showing only the background image, no app icons, no interaction possibile. I tried rebooting and then booting in fastboot... in the latter case the Note get stuck with the orange fastboot logo, not the one with the image.
I suppose an overnight update went wrong... but I can't be sure.

The device has never been rooted or manually updated.

Does anyone have any advice?

UPDATE:
I can reach the device via fastboot from terminal. Adb doesn't see the phone.