Certain models such as iPhone 5s, iPhone 6, iPhone 6 Plus, and iPad Air 2 encountered Touch ID malfunctions after upgrading to iOS 8.3. Despite the numerous improvements and bug fixes in iOS 8.3, some users prefer to revert to iOS 8.2 due to these issues.
Guide to Downgrade iOS 8.3 to iOS 8.2 for iPhone and iPad
Step 1: Download the iOS 8.2 IPSW for your iPhone or iPad matching your device model here: Download iOS 8.2
Step 2: Put your device into DFU mode by simultaneously holding down the Power + Home buttons for about 10 seconds. Then release the Power button and hold the Home button until the iTunes message appears, then connect the device to iTunes.
Step 3: Press and hold the Option + Alt keys on Mac or Shift key on Windows, then select Restore iPhone.
Step 4: Choose the IPSW file you downloaded in step 1.
Step 5: Click on Update to begin downgrading to iOS 8.2.
https://Mytour.vn/ha-cap-83-xuong-ios-82-cho-iphone-ipad-2169n.aspx
After a few minutes, your iPhone will automatically restart. Enter your password and wait for the device to finish updating. That's it, we've guided you on how to downgrade iOS 8.3 to iOS 8.2 for iPhone and iPad. Follow these steps sequentially for a successful process. If previously people wanted to downgrade iOS 8.3 to iOS 8.2 for the purpose of jailbreaking their device because iOS 8.3 was not jailbroken, but as of now, you can completely jailbreak your iOS 8.3 device using TaiG software without needing to downgrade to iOS 8.2.