It's has happened to me, once a week or so, the last time about 33 hours ago. I go to use the phone and it is dead and has to be rebooted. I suspect it is some app that is causing the problem but I have not discovered it yet.
Same problem here which started last month. Tried to remove some apps but to no avail. Tried to reformat it to its factory setting 3x but unfortunately, still the same. It keeps on shutting off with almost 80-90% battery. The only way that I can use my note in the last few weeks is if it is plugged. Please anyone who can help will be greatly appreciated. Thanks.