Unable to upgrade/update iPad 2 from iOS 5.1.1 (to iOS to 9.3)
Welp, I resolved this problem, or rather, iTunes decided to resolve this problem for me after some hesitation; it finally prompted me to update the device (after telling me it wasn't supported -_-). So if you're in my boat and exhausted all of those "turn it off and back on"-esque options, hopefully fidgeting with iTunes grants you the opportunity to update.