Can't enable iCloud backup on my iPhone
I've spent 3 hours with Apple staff, and I've made no progress. I'm attempting to backup an iPhone 5 to iCloud. Under settings>iCloud>Backup, it shows "Off". iCloud Backup button/switch is greyed out and can't be turned on. If I connect the phone to my desktop and attempt backup through iTunes, it tells be that Administrator has disabled iCloud backup on the device.
At Apple's instruction I've updated the software to 10.0.2 on the phone, I've updated iTunes to the latest version. I've signed out/in of my iCloud account, find my phone, etc. twice already, and I've backup up the phone on my desktop twice and I've synced the phone twice.
Any ideas how to enable the iCloud Backup switch on the phone or what is preventing it from being enabled?
Note all the actions already tried.
Thanks!
iPhone 5, iOS 10.0.2