Reactivating a Phone Without Service
I finally figured out how to fix this. I don't know if this is the best way to do this, and if this is unique to just this phone, but here's what worked for me:


Rebooted the phone
Unlocked it at the lock screen that popped up
When I came to the activation setup pages, I pulled down the notifications shade
"Quick Settings" >> "All Settings" >> Home Button


I'm not sure how exactly this worked (glitch or bug, maybe?), but it did. Thanks for all the help!