I have an HTC One M8 running Marshmallow 6.0, kernel 3.4.0-perf-gd7aafa47 and build MRA58K.H15, unlocked bootloader but non-rooted device. The device is a tab over 2 years old now, and the system has been shutting down on its own when the battery charge gets closer to 10%. Yesterday, after charging up and powering on, I've noticed no more notifications are shown. The sounds are played, but no icons are displayed at the top left. Further, when I try to draw down to see more information, nothing other than 'No notifications' message displays. Also noticed that the gear icon on the top right has disappeared, I actually have to go the long route to access settings now. Another thing I've noticed is that the 'developer options', which were always enabled, now display '...not available for this user'. I've tried wiping the cache partition, but that made not difference.