I still experience deep sleeps without the possibility to wake the phone with power button while changing.
These episodes happen only while charging (during the night) if the phone is not used.
Every time when that happened, the WiFi was ON and connected to my home network. Mobile data was on too.
Also, during these ?unresponsive deep sleep sesions?, the charging LED is always ON (although the phone is not responsible) and if I plug out the phone from charger, the LED is still on (and green, sign for ?battery is full?). That's means the phone is somehow blocked in an unresponsive state.
If someone calls me during this phase => it appears I have shut down my phone. Also, alarms or other app doesn't work at all.
Long pressing the power buton (>10 sec) force-reboots the phone but the battery shows it is not fully charged at all (<90% most of times). I find this annoying.
I've heard that there are similar cases with Lumia phones. It is that true? Is this a hardware problem or an OS bug? It's quite hard to duplicate.