No service and I want to re-install the new update

See if the tips in the following article helpp resolve the issue.

If you see No Service or Searching on your iPhone or iPad - Apple Support

If not, then see:

iPhone 7 Repair Program for "No Service" Issues

You cannot install an iOS update via cellular. Either use wi-fi, or connect the device to a computer with the latest version of iTunes. If you wish to restore to factory, you will have to use iTunes. Update your iPhone, iPad, or iPod touch - Apple Support

You need an internet connection to connect to the Apple Server.

Can you get on wifi if you have no cell service?