Sprint Firmware - Galaxy S3

: Be aware that early OTA (over-the-air) updates specifically removed the "Universal Search" feature from the Google search bar due to legal disputes, restricting it to web-only results. Helpful "Paper" & Guides

: The last major official update for the Sprint Galaxy S3 was Android 4.3 Jelly Bean (specifically builds like MK3). Sprint Firmware Galaxy S3

: A small hardware tool that can force the phone into "Download Mode" even if it won't turn on normally. : Be aware that early OTA (over-the-air) updates

: A comprehensive Sprint S3 ROM list details community-made firmware (like CyanogenMod 11) that can push the device up to Android 4.4 Kit-Kat . : A comprehensive Sprint S3 ROM list details

Are you looking to settings, or are you trying to upgrade it to a newer version of Android via custom software?

: For users on the final 4.3 firmware, the Saferoot method on XDA is often cited as the best way to gain control without tripping security flags like Knox.

While physical manuals are rare now, the following community resources act as the definitive "papers" for this device: