iPhone 11 Pro: Unable to Activate, an update required - Multiple error

Hello there!

I have bought a broken iPhone 11 Pro that fell out from a car and other went trough it.

The damages are the next:
-The water indicators are red, but I can’t see liquid damage on the main board.
-The screen is cracked to the pieces along with the back.
-The sensor-module on the screen is damaged. (As I know it is the one that paired to the phone - bad luck).
-As I think, FaceID is also damaged, because the phone was getting warm and kept rebooting if connected.
-Back camera is surprisingly works fine - I have Tested it.

Continuing the story, I have bought another iPhone 11 Pro, that is disabled by the carrier for not paying bills, but in mint condition. So I decided to use the other phone’s mainboard.
I have swapped the mainboard, and reprogrammed the screen (I know, I have to replace the chip on it)
The first problem came here:
I bought the broken one as iCloud free, the seller stated, they have logged out on PC, and as I checked the IMEI, it was clean and FMI was turned OFF also, but I couldn’t log off from the iCloud because: “Sign out is not available due to restrictions “.
In the options, I saw, there is no carrier restrictions, so I put my SIM card in the phone, but there were no carrier name in the top-left corner, neither “No-Service”. I have checked again the Settings, and it recognized my SIM-carrier and WiFi was working.

I have decided to update the phone to iOS 15.1, but it was always error 9. I thought it was because of cable, and tried other cables with the same result along with DFU and IPSW (I have tried everything and every combination). It was always sending error when iTunes tried to install the firmware. Then came to the mind, maybe the screen causing this problem and I was right - after I disconnected the screen and put the phone to DFU, the restore and update process was succesful(was it?).

I have put back the working screen and “Hello Screen” came. The next problem started here, as I stated in the title. “Unable to Activate. An update is required to activate your iPhone”

This is where I stuck now. I have tried almost everything, put back the broken screen with the damaged sensor-module, put in the SIM card that was came with the broken phone, also with my SIM card and tried to activate with 3uTools but nothing.

Do any of you have some clue/idea/advice what to do next or is it a non-fixable thing?

Thanksif you read this long post!