This is a bad baseband. This prevents the device from activating. Here is why
During activation, your device sends out its unique identifiers to apple, and after it is checked if it is locked or not, you get back either an activation ticket, or an activation lock screen. (Random fun fact, this server is called Albert, say hi to Albert)
So as you can guess, when the baseband fails, you lose your IMEI. Your device sends out its unique identifiers but it’s missing its IMEI. This makes Albert very sad, and he doesn’t know what to do. Therefore you get this. It says you just need an update but doing as it says doesn’t help.
Basically, you get left with an expensive paperweight.
It’s a hardware problem. Bad baseband. If you look up I’ve got a comment laughing at all the comments like “I’ve had iPhone since 3gs no issues” and explaining it not in depth, then I have another that goes in depth on the issue. Anyways if you don’t believe me, here’s a bad baseband 12 for example.
https://preview.redd.it/8utt6bpxb1xb1.jpeg?width=2268&format=pjpg&auto=webp&s=06dcaa4d6b7e2f05c69dcccfdd0749f817535acc