I always like reading the usual suggestion reset your phone to factory defaults this is the cure all for the world's crap software problems.
Will let me tell you if you have the misfortune of having to reset your phone to factory defaults while you running lollipop you are screwed beyond your wildest nightmares. Because lollipop restricts all apps to only being installed in internal memory it is impossible to restore your phone from a backup because inevitably the phone runs out of internal memory so you end up with this completely corrupt piece of crap paperweight. To add insult to injury the phone is not backed up in its entirety to Google so although your apps and restore all of the settings for your apps do not.
So there's no question in my mind that Android is written by a bunch of an experienced coders you have no idea at all what regular users are going to go through with their software.
I have over 30 years of experience in software development and network integration and I can tell you that the software in this phone while it is very impressive what you can do with it it is out early crap it has no sensible integration testing anything like that done these phones can still barely make a phone call and sms. it's terrible to see the quality of software that's being put out in the market place that people are expected to buy and live with.
I truly pity anyone who does not have a throat and logical background dealing with these kind of phones.