Keeps restarting, stuck in Ultra Power Save Mode I'm asking on behalf of a family member who has a Samsung Galaxy S5.  The phone is unrooted and has been updated but not to Android Marshmallow.  The OTA had not been released for Marshmallow for this phone by our carrier.  

There were many previous issues months ago but permanently removing the SD card and a firmware update through Samsung Kies solved those.  The phone has had no significant issues for the last 5 months.  

Recently, the phone was put on Ultra Power Save mode to save battery life.  Immediately it shut itself down and kept restarting into Ultra Power Save mode and has done this for 3 weeks.  

When it starts there are a few seconds before it restarts again.  The screen is grey (no color) and most apps are disabled or not shown.  The settings menu has very limited functionality and there is no way to disable Ultra Power Save Mode.  

Going into safe mode does not change anything (the phone just restarts again in a few seconds).  I've gone into Recovery Mode and cleared the cache but that did not do anything.  I have not done a factory reset as I would be losing a family member's numerous wedding pictures if I did that.  

The phone has not had any physical damage.  It is out of warranty but locked to a 2 year contract.  The only solution to stop it from restarting is to remove the battery.  

Is there any way to get it out of Ultra Power Save Mode?  Would a factory reset help at all? We really would prefer to do that as we would lose the many pictures.  I read about bootloaders but I don't understand that well enough (also note that I've permanently removed the SD card -- if I would need that in order to use this feature).  I read something about trying commands through Google Now but I can't do that unless I am doing it wrong.  I tried connecting the phone to a PC and starting Kies but Kies does not recognize the device (as the device is not on long enough).  The PC itself only recognizes the device for the few seconds that it is on.  I've tried charging it, removing the SIM card, and also leaving the phone off for days but nothing has worked.  I use Ultra Power Save Mode often on my own phone but had not used it on this phone before.  

Thank you for helping.
You can always backup all of your photos and everything else to a Google account (here tells you how), and then factory reset the phone. 

If this does not solve the problem, it may be worth taking it into a shop to see if they could do anything, or contacting Samsung directly. 

Hope this helps