For many years apple users have been struggling with common board issues that were not fixable for the longest time and now apple has came up with certain recall programs to help assist those manufactured defects. Iphone 7 has been known for No service or no signal issues and majority are defects found on specific model A1660. If your iphone 7 is A1660 model then it may qualify for no service repair program.
Check out options to repair your iphone 7
Click the link below for more info.