The proximity sensor doesn't work, many times when I call the screen doesnt' turn off. I also have some problem with gravity sensor, the screen doesn't rotate. I check sensors answer with an app, and the sensor values holds at 0.
After a reboot gravity sensor works for a while, the proxyimity on the contrary doen't work after a reboot, it works when it want for few minutes and no more.
I tried to remove the screenprotector and to do an hard reset, but I got the same issues also before app and account restore.
Now I don't know if I should send it to assistance of to try to downgrade to android 4.2, what do you think?
May I lose warranty if I try to downgrade?
It is a bit strange issue because sensor sometimes works so I can't be an hardware problem. However I don't remember this issue with the first os versione 4.2 but only after the update to kitkat.
Thank you for your suggestions.