How to update your iPhone 11

If you have either dropped the device accidentally or exposed it to liquid or used it beyond acceptable temperature limits then…

Take your device to an Apple Retail Store or Apple Authorized Service Provider, or contact Apple Support:

Find Locations - Location Selector - Apple

Contact Apple for support and service - Apple Support 

Get a Genius Bar Reservation and Apple Support Options - Apple

Contact Genius Bar.

Manage Reservations - My Reservations - Apple

Can you explain with details, what you meant by “acting weird”?

What happens when you attempt to update your iPhone? What do you see on the screen?

Axel F.