yesterday, I just swapped my sim card for some time with another. Placed it back....and voila! I can't enable data connection. I lost all my apn settings. To add to this, neither is it auto fetching the apns, nor i can manually change it! It shows some fucking error "apn settings not available for this user". I have another phone with same android version (lollipop) and everything works smoothly on it. These guys just broke everything after giving an upgrade from kitkat. Auto brightness stops working after a few hours, random reboots.... This is it... bye bye stock rom!