Is there a problem with iOS 8.1 on the iPad Mini?

I’ve had my iPad for around 3 years. Worked just fine, never dropped it or broken any screens or anything. Yesterday morning it began asking me for Apple ID password and authentication number whenever I open any app. If I type everything correctly, it just resends another code. If I don’t submit anything, the app crashes. Literally no app (music, safari, YouTube, etc.) works except the App Store and the settings. When I go to sign out of my iCloud, I get an authentication error. When I try updating my iOS I get another error. Plus I can’t plug it into a computer because it won’t connect to it. The charger icon just turns on and off repeatedly. Don’t know how to fix. Tried restarting both normally and by holding the power and home buttons. Don’t know how to fix.