[adock22096]

Well I was hoping the marshmallow update would fix the random restarting my phone does but it didnt. It's gotten so bad I can't really use it anymore.
I tried replacing the battery but that didn't help. I tried a factory reset, and that didn't help either. I've noticed the top 1/4 to 1/2 of the screen gets warm when it starts acting up?
Does anyone have any idea what could be causing this?

[nahoku]

Have you tried cleaning the contacts on the phone and battery. I recently had a random restart and I normally have everything turned off (wifi, data, location, apps, even all google apps unless I need to run them), and I'm on Kitkat. I think fast charging builds up more oxidation on the contacts. I cleaned mine up using an electric pencil eraser... nice and shiny now. This was my first ever restart on it's own, so I have to keep an eye on it.

[adock22096]

Yeah I tried that too but that hasn't helped.

[nahoku]

There is a lot of speculation about how these random restarts are happening. Since I don't use social media, and don't sync anything, and my wifi, data, bluetooth and location is mostly always off, and I also force stop any app from running unless I'm using it (that includes all google apps killed), I was very surprised when my phone restarted on it's own. Basically my phone is just used as a phone unless I need to do something else. Kind of a hassle to run my phone like this, but I don't mind since I really don't do much on it unless I'm out somewhere.

The point is, with the way I run my phone, plus it being on Kitkat, kind of takes all the apps and OS updates out of the picture as being the cause of my restart. In my case, I have to look at hardware being the cause. My battery was at 61% when it happened, and directly after the restart, the battery was still at 61%. I own 3 original Samsung batteries so that also takes 3rd party batteries out of the picture. After the restart, I shut down the phone, cleaned the contacts on the phone and changed the battery (cleaned the battery terminals before installing). My phone was also very cool before and after the restart, so no high/unusual temps involved. Again, this is the first restart I've had in close to 21 months, and for 3 days, I haven't seen another one yet.

THIS PAGE shows the component layout of the motherboard. Looking at it, shows what components might have been getting warm on your phone. The processor sits upper left (opposite battery terminals) so if it's getting hot, then it's working too hard for some reason.

The only thing I can think of is start the phone in Safe mode and put it in airplane mode so all the radios are off, and run it like that for a while to see if you still get a restart. Something must be taxing your processor.