Iphone Xr unable to activate

Hi:

It started with cellular data unable to update, need to update network, etc

I did a reset, then itunes needed updating because there was a 'no permission' warning

Then 'unable to activate' an update is required to activate your iphone. Learn more at apple.com

Followed all the steps for that one, restore via itunes, update, downloaded 14.4 ios and tried to instal, nothing worked. I could not find a signed 14.3 to try that, so nothing I have tried works.

Phone = 1 1/2 year old