The iPad will now contact Apple. Because Apple still signs the OTA delta update for iPad 2 (from 6.1.3 to 8.4.1), the server will send the full 8.4.1 firmware.
This method works for the iPad 2 (Mid 2011). If you have the iPad 2 (Late 2012 / 4,1 Revision), this specific method may not work. downgrade ipad 2 ios 9.3.5 to 8.4.1
Apple’s OTA update system checks which versions are allowed between specific iOS builds. By faking your current version as an even older one, the update server offers 8.4.1 as the intermediate signed version (because iOS 6 → 8.4.1 is a valid OTA path). The iPad will now contact Apple
This is a story of a "legacy" iPad 2, trapped in the sluggishness of its final official update, and the digital bypass used to bring it back to life. The Problem: The "iOS 9" Slump The iPad 2, released in 2011, officially supports up to If you have the iPad 2 (Late 2012
Why can't i update my ipad mini 1 to ios 10? - Apple Support Community