"An update is required to activate your iPhone"
iPhone 11 pro max 1st issue was the volume and camera weren't working and the phone would turn off and on by itself. Then started having issue of it not connecting to my cellular. I took to my carrier and they gave new SIM card and reset settings still same problem. Phone is now not connecting to my cellular I backed it up and restore it and now it is saying an update is required to activate your iPhone but the phone is up to date. It also is not connecting to my Mac giving me the message of Activation Failed so I cant view the phone at all. Help??
iPhone 11 Pro Max