I have had similar rebooting problems with my Note 4. Like others it all started with the Marshmallow update as the phone would very sporadically reboot, usually 6-10 times per week. I had no issues before and really loved my 32gb Verizon Note 4. The reboots would happen at random, sometimes when under heavy workload and sometimes I'd pick up my phone after an hour of non use charging to find a password prompt because the phone had rebooted. After having the phone reboot during a VERY important business call, I was fed up and began investigating solutions.
Many suggestions I saw online said to try a factory reset. I hate having to factory reset, it's an absolute bear getting my home screen back to the way it was. But to fix my phone, I bit the bullet and did it. No dice, the rebooting persisted.
Next I got on the phone with samsung and long story short, ended up making a thirty minute drive to my nearest best buy to have them reflash the software. The tech there was very nice and helpful. After performing the reflash he advised me to call samsung if the issues persisted. For about 48 hours I was convinced the issue was behind me and my beloved Note. But once again the phone cracked and rebooted in the middle of a workout at the gym.
The next step was to call samsung as the Best Buy tech had instructed. I phoned them up and had a repair scheduled. The guy also informed me that the samsung 1 year warranty had just recently expired. I agreed to send it in and was provided a free shipping label. After a few days, I got an email saying the techs had received the phone and done their inspections.
I was going to be charged about $70 to fix the phone and have it sent back to me. Now I must admit, this isn't a bad price to supposedly fix the issue but I must preface it by saying my phone was in IMMACULATE condition. It's been in a very durable case all its life and never outside a tempered glass screen protector for more than five minutes. It's what angered me most about having to pay for the repairs, they weren't my fault. I'll also add that my phone is my daily workhorse (as I'm sure it is most for most). I need my phone to handle every daily task I throw at it without a hitch, exactly the selling point of the Note line. The Note is marketed as a phone for the power user. One that needs something a little more than an ordinary phone.
As a last ditch effort, I called Samsung again to dispute the fee. The guy was once again very helpful and told me some parts needed to be replaced. That seemed odd to me given that I had taken such good care of my device. I had him call the service center but they were no help. They told him they were replacing 'general parts'. 'Nothing specific'. But then when I eventually paid the $70 the description of my repair stated 'Software Update / Mobile OS Updates / Software Reflash HEZ21'. No mention of parts replacement. Also no mention of what exactly the issue with my phone was.
At this point my phone is on it's way back and I've made up my mind for what I'm going to do. Sell the Note and buy a Nexus 6P. Based on the widespread difficulty people are having, it seems the Marshmallow update is the main catalyst for the issue. A common theme with android phones that have skins over android is that they don't age well. Issues pop up and phones bog down with each new version of android, especially on heavy skins like TouchWiz. A shame really given the impressive hardware and the fact that it's one of the last flagships to have a removable battery in addition to expandable storage. It's really a phone that should've lasted for my full two year contract but is let down by half baked poorly optimized software. I'll really miss having the S Pen for doodles.
Anyone else please let me know if you've had a similar experience!