Go through all of the steps listed in: http://www.fireebok.com/resource/five-ways-to-fix-mobile-data-updated-failed-on-iphone.html
The last step listed says:
5. Apple provide the repair program for "No service" issue for iPhone 7 for free
Because of a component that has failed on the main logic board on a small percentage of iPhone 7 devices, Apple will repair your device, free of charge. This program only applies to iPhone 7. If the model number of of your iPhone 7 is A1660, A1780, A1779, it may be eligible for this repair program. And You can find the model number on the back of your iPhone 7. Learn more about this program here(https://www.apple.com/support/iphone-7-no-service/)