Nokia Lumia 925 Windows phone keeps shutting down

Question

     I have had a problem for the past 2 months, my Nokia Lumia 925 with Win 8.1 keeps shutting down spontaneously. (I did not have this problem before 8.1)  This is my third phone in the last 2 months (warranty program keeps sending me replacements) and it shut down for the first time this morning. All 3 have developed the same problem, the phone will shut down spontaneously and the only way to start it up again is a soft reset (Volume down + Power for 15 seconds). I have had a total of 10-15 shutdowns between the 3 phones and this is a conservative estimate.
     I am thinking that this has to be a setting or an app that I use (and few others do) that is causing the shutdown since I have only seen a few other similar issues in the forums. Here are some of the basic facts about my situation and some of the actions I have taken:
              - I have wiped the phones repeatedly (3 phones wiped a total of 3 or 4 times not including the initial setup of the replacement phones, which is getting really old--really fast).
               - I have tried turning off NFC, but that obviously  wasn't the issue because NFC was off this morning when it shut off.
                - I have tried trimming the screen protector/screen guard I installed as suggested in one of the other forums even though that seemed ridiculous (I think that was a different model phone too, but I gave it a shot)
I have not noticed any common occurrence such as
                           --when a certain app is running
                           --when it is on/off charger,
                           -- When the battery is full or low (it was 24% this morning).
               -I have 2 chargers, 3 if you include the car charger that I have never had to use due to great battery life. 
               - I have called tech support several times, all AT&T can tell me is that this is not a known issue and I should wipe it again. Nokia says the same and that I should send it back to them for repairs. That seems fruitless to me because I have had 3 different phones, what are they going to repair that a new phone won't fix?
       It takes me 3 hours to reinstall and set up my apps, I am getting very frustrated. I really love the way this phone functions, the software is good, the screen is brilliant and very sensitive, the camera is great (although a bit slow), and the size and feel are perfect for me...I hope that someone here on the forums can help.
Thanks for your help in advance...
Al

Answer 1

Hello, mariaadamsky.
We appreciate you reaching out to our community regarding your concern. You are using a Lumia 925 as well, correct? Did something happen to your phone that possibly caused such behavior? Did you try doing fixes on it? 
Latest software released for Lumia phones is the Lumia Cyan. To confirm that you have it installed on your phone, go to Settings> extras+info. You can also try going to Settings> phone update> check for updates to check if there's an available update. Are your system apps also updated? While connected to WiFi, go to Store> ...> downloads to check for pending updates. Let's hope that the phone will not shut down while doing this process.
By the way, we can try other fixes that could help us identify the real cause of the issue. In case you wish to have it repaired in a Nokia Care Point, warranty claim may vary per region and Nokia does not have an international warranty. Also, creating a backup is a must to avoid data loss. Where did you buy the phone and where are you located right now? To know about the manufacturer's limited warranty, go here: http://nds1.nokia.com/files/support/global/phones/guides/Nokia_Manufacturers_Limited_Warranty_with_W.... 
We look forward to your reply.