Also, I wasn't doing anything weird with the phone when it died. I hadn't downloaded any third-party apps recently.
I've downloaded over a dozen different apps that cause my phone to go bat crap crazy. Sometimes it happens as soon as I open the app, other times it may be a week or more later. I posted the issue here, but apparently there isn't a solution other than uninstalling, which is quite a chore as getting into settings can be like walking through a maze. Almost all ran fine on my Samsung (seems to be a common remark about the Turbo).