I am having issues with my iPhone 6 Plus. Since updating to iOS 11.2, and I hope I'm not blaming that unnecessarily, the phone has been slow to respond, the battery seems to be running down quickly and now the phone crashes every 1 - 2 mins, after which it asks for my passcode and works for about a minute then crashes again. I can make calls as long as I wait for the screen display to show and the call continues when the screen display shuts down. It's driving me crazy. I have done all the obvious actions - soft shutdown of apps, hard shutdown and restart of phone, I've cleared off unnecessary apps so there is plenty of room left on it and I've backed it up manually as well as automatically. Any suggestions for my next step please? I need the phone to operate my Square Card Reader for my business and this can't happen, as it is.
See existing thread Clicky
As you've backed it up (hopefully with a password as it'll save extra stuff) I can only think restoring the phone as new and run from there?