Does Xbox install updates when I do a "full shutdown"

Even in full shutdown? I assumed Full shutdown fully powers it off so that it is safe to pull the plug...

Yes, it will wake up at an appointed time and check for system updates. I don't think it will do games in power saving mode.

The first thing i would recommend is to do a full shutdown of your Xbox, by holding down the power button for about 10 seconds. Then from that if it won't update, attempt to do a full installation of Fortnite and make sure that you have a significant amount
of storage to install and update it. Sometimes it will not tell you if it needs additional storage and won't update.

This is happening to me , but I'm in the insider's. It's a black screen but if I hold the xbox button it dose show the option to shutdown or restart. If I back out of it my home screen shows. Strange one . 🤔

I'm in ASA insiders, and find it's better to do a Full shutdown after an update,

(2-3 a week). I also have Energy save mode not Instant on and do the updates manually.

It's good practice to do a Full shutdown at least once a week if you use Instant on, imo.

Idk if this will do anything but if you do a full shutdown, and turn it on again, it may update them.