New iPhone 8 Plus will not load iCloud backup

I went to the Apple store yesterday (11/10/17) and traded in my iPhone 7 Plus for the iPhone 8 Plus. I did an iCloud back up at home and at the Apple store.

iPhone 8 Plus would not recognize my iCloud password. Changed password after I got home, and reset the phone. Tried to reinstall the backup, but only gets to a certain point and keeps asking for my iCloud password.

Contacted Apple support and they want me to restore my phone via iTunes on my computer. This is a brand new phone! I should not have to do this! I am seriously thinking about going back to the Apple store today and having them replace the phone with a brand new (not refurbished) iPhone 8 Plus since problems on the first day of ownership do not bode well for the lifespan of this phone.

Opinions?