Q: I was in process of installing upgrade to my phone and it froze!! I cannot get pass that screen.

Sorry, but it seems that this is related to the recent iOS9.

If the Slide to Upgrade screen won't go away after you update to iOS 9 - Apple Support

The only way to get your phone working again is to set it back to factory settings, without using the backup data.

Click on the the blue link in my last post and you will be able to read the info given by Apple.

Apple promised:

This will be resolved soon in an upcoming iOS update.

copied from If the Slide to Upgrade screen won't go away after you update to iOS 9 - Apple Support

Reset the phone by holding the sleep and home button for at least 10 sec until the Appel logo comes back again. Then connect in recovery mode.

These steps are described in this article:

If you can't update or restore your iOS device

After iTunes detected your phone in recovery mode, choose to restore the phone and after the new software got downloaded and installed by iTunes, set it up as new device instead of choosing the option to use the latest backup.

This DIDN'T help me.....but would''t let me uncheck that it did!!!  So, if you can't activate the "slide to upgrade" after you were instructed to "continue to upgrade", but you cannot do a "restore" because you cannot access your phone to deactivate the "find my phone" feature.....THEN WHAT?!?   This is the worst start to an "upgrade" EVER.