FYI It may be a one off but I have just run the diagnostic test (with the latest firmware) and once I had come out of it the hardware buttons would no longer function (which was fun
as I could only wake the thing up by plugging a charger in!) I had run all tests and deleted the app and bingo, no keys! I ran the diagnosrtics again, this time just for the hardware kays and this appears to have resolved the issue.
HTH