BIG CLUE ON POSSIBLE CAUSE!!!
Folks, I think I have an answer for this restarting problem- but I will need the help of others smarter than me to push this over the top and get us a solution.
I think the problem causing the rebooting is (Drum roll please...) >>Increased internal operating temperatures.<<
Here is what leads me to believe that:
I have an ATT Samsug Galaxy S5 I bought about 1 month after the product was a "just released". I currently have it on ATT/Cricket. I NEVER had an unintended restart until about 4-5 months ago. Then, it started happening all the time. Sometimes within minutes of each other. No predictable pattern, no specific app use. Even happened when it was simply sitting on the charger "sleeping".
It was making me crazy.
I also noticed a few months ago, i started having incredible battery drain. What used to be 2 days to a charge, now would get chewed up in 1/2-1/3 of a day. Also it seem the phone case was getting awfully hot the last few months - and I NEVER noticed that before.
I tried installing clean Master and various battery protection apps, fast chargers etc. It seemed that the phone always getting warm to the touch - even the screen, which seemed weird.
The battery drain was annoying, but then the restarting began and made me crazy. I first noticed it while texting, then later on the phone, then on browser, and finally any time, any app.
I tried uninstalling Facebook - seemed to help, but not stop the restarts. Tried doing resets, changing default settings, eliminating suspicious apps etc etc. which helped some but still had the restarts.
Then an even happened which gave me the insight - I was at an outdoor location (musical event) where my band was performing. As usual, I put the phone away safe during th gig in a black fabric case with my wallet and watch. Because it was a hot day outdoors, I put in under a table.
When I came back, I saw the sun/shadows had shifted, and my black case was in the direct sun. I opened it, and the contents inside were hot. I turned on my phone and thankfully it started. But then it began to restart, and restart and restart. i felt the back case and it was burning up! I rushed it into the gift shop, into AC and pulled the back cover off, pulled the battery and put it under the AC vent until it was cool. Guess what? The restarting behavior vanished :-0
So here is what I think, but can not prove:
The latest version/update of Lolipop/ version 5 has an internal incompatibility with some of my pre-existing apps that allows them to "run wild" in the backround increasing device temp. When it senses a high temp it shuts down.
Other possibilities:
1) The temperature sensor is broken
2) Battery temperature is the issue, not device temperature
3) Battery is shorted causing the high temps
4) Case is not allowing adequate ventilation (I have a Kraken Trident heavy duty case)
5) Device itself was fried from a high temperature encounter
6) Maybe it is shutting down for another reason and high temp is an effect but not cause.
Nevertheless - a temperature issue fits much of what I have read on this forum.
I have downloaded a temperature app and will see if I can document temps that are present at restart time. Then if we can find a critical temp, maybe we can find out why this is happening: software, hardware or battery.
Mull this over and see if it fits your personal observations with this restart problem. I await your observations and input.