my sons iphone 7 has a cellular error i followed the step to update it and it restored and updated it and now it says unable to activate what can be done to bring it back ?

Hey there, creed8187!

Thanks for reaching out in Apple Support Communities! We understand you updated and restored your son's iPhone 7. If your son's iPhone 7 is eligible for the "No Service" program, then you can set it up for service. Here is an article for that: 

iPhone 7 Repair Program for "No Service" Issues - Apple Support

If you set it up for service, please follow this article before going into a store: 

Get your iPhone, iPad, or iPod touch ready for service

Take care!