iphone 12 promax just died after latest IOS update

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If the Restore screen appears on your iPhone, iPad or iPod touch – Apple Support

If that fails arrange a repair 

Click here > iPhone Repair & Service - Apple Support 

Or  Click here >  Contact - Official Apple Support 

Anything other than Screen or Battery may be a replacement phone and the price is in the article under "Other damage" 

See also:  Get your iPhone, iPad, or iPod touch ready for service - Apple Support 

There is no compensation for hardware that fails during an update. 

Hi!

It looks like your iPhone has entered Recovery Mode. In this case, you can exit Recovery Mode. But first I want to ask you some questions: have you tried updating your iPhone from the Settings app or from Computer? Also, has the update started or has your iPhone entered Recovery Mode before the update?

That said, I’ll explain how to quit Recovery Mode on iPhone:

1) Connect your iPhone to your Mac or PC.

2) Now perform a forced reboot on your phone. To do this press and quickly release the Volume key on. Quickly press and release the Volume Down button. Hold down the side (power off) button until you see the Apple logo. It must be a very, very fast procedure. Hold down the side button for 30 seconds if necessary, but the most important thing is speed. To help you, you can remove the cover (if any).

Now your phone should be out of Recovery Mode.

If your iPhone is still in Recovery Mode, try this solution:

1) With your phone still connected to your computer, open the Finder (on Mac with MacOS 10.15 Catalina or later) or iTunes (on Mac with MacOS 14 Mojave or earlier or on Windows PC) and select your iPhone in the sidebar. You should ignore this step if you get the message " There was a problem with [your device name] so you need to update or reset your device" and go to the next step.

2) Click "Update". This will keep your personal data.

If the problem persists, contact Apple Support.

I hope I helped you!