....have you been looking at the screen all day, or have you restarted it?

You could learn to speak Spanish? Sorry I'll see myself out

what do you mean stuck? nothing happens when you select region? try a reset?

Does it has a reset button or pin which you can press? there should be something there.

You can try a hard reset.

https://www.hardreset.info/devices/xiaomi/xiaomi-mi-box-s-tv-4k/

I'm pretty sure it's overheating and throttling

My stick does the same when I do something heavy, like sync a Kodi library

I had the same on my MiBox 4K after I performed the update.

I pressed the Back and the Circle button on the remote whilst it was still on the Region Mexico screen and the Remote synched to the device within a couple of seconds and let me then scroll to my region. Hope this helps someone else out there