Iphone XS frozen since update
I recently updated my iPhone (to 10.4.2?, the latest) and today, moments after I started using it this morning, fully-charged, it stopped working. I can't get it to respond in any way. When I went to shut down/restart, it is now stuck. Holding the two top/side buttons activates SOS Emergency (though neither an ambulance nor police have showed up, and my family hasn't written in alarm) but it won't shut off.
The only thing I can think to do is wait all day until the battery dies, then hope a restart makes it function again.
Any alternative fixes would be dearly welcome.
iPhone XS