I had a long night yesterday, and at 5am my Xperia had like 10% of battery left, so I put it in Ultra STAMINA mode and fell asleep. This morning, the phone wouldn't turn on as the battery was completely dead. So I came home, charged the phone a little and turned it on.
Now, it's not in the safe mode, but it looks like that! The default launcher is operating, but I can't switch between none of the launchers neither. I can see only very few applications, and when I turn them on, they shut down immediately. When I reboot the phone, the first message is that Google Play Services has stopped working.
Now if I go to
Setting -> Apps, I see everything there! Launchers, apps, games everything, also photos and contact are all there.
The Ultra STAMINA mode makes your phone use only the basic functions and I'm pretty sure it turns on the default launcher. Also connecting to computer does not work neither!