Phone: LeEco Le S3 x626 Android: 6.0 EUI version: 5.8.018S (Stable it says, and this is what I got the phone with originally, I did not modify or change the software)
Well, I probably have the weirdest phone problem ever. It all started about 2-3 months ago. My phone suddenly started doing that: I was listening to music (perhaps just a coincedence, since I do it a lot) and the signal suddenly ceased, and when the phone was sleeping, I could not open it up with my fingerprint (it did not even vibrate when I tried it with my wrong finger) nor with my pattern. Then, when I restarted the phone, during startup, under the EUI logo (that's the software), not the usual "Inicializing apps" showed up but instead "Optimizing apps 1 of 2", and it did not start up, only after a LOOONG while. Then, after PIN and a few minutes of having proper signal, the same no-signal-no-open-thing happened no matter what I did. It went on, until I tried resetting the phone, which deleted all the apps including my Dub Music Player, which I had been using for a while without problems (downloaded from Google Play of course). So I tried re-downloading it, and the same problem happened, making this player the suspect. Then, after a few tries of getting an earlier version of the app from browser and finally another full reset, I did not download the player again, I switched to Black Player (you might question why music players matter that much, but this is one of the main things I use my phone to (I need to have a proper structure and a proper equalizer and stuff) and the stock player is poop) and I did not have any issues until now.
Right now, my phone has no signal. If I pressed the power button, all that I've just written above would get lost. The only difference now is that - as I figured it out by restarting the phone - there is no "Optimizing apps 1 of 2" sign, the phone boots up properly, I get signal and everything's working properly until the signal suddenly disappears and you know the rest.
So this would be my problem, I'm sorry that it got that long but I had to be specific, because I have never heard of any problem like that, I cannot find any rational reason for it. (But perhaps it's a somewhat common thing I'm not aware of...?)
Thank you for the answer in advance ;-;