Lumia Icon :: Why Does Phone Lock At 6:40am

A few days ago I woke up late as my alarm didn't go off. I had it set for 640am on weekdays and have been using it this way since I bought it in July. I pulled the phone off the charger and the screen would not wake up, it seemed dead. So I held down power and volume and it reset and came up fine. Until it happened again the next day... Now, I had woken up around 530am and checked my phone for the time, it was fine then, I went back to sleep and when I woke up after 7 (late again for work) the phone once again, would not wake up and I had to reset it.

So, I went to work and did a full software reset and went through setting up my phone. I set my alarm for 5 minutes earlier, 635am and went to sleep without plugging it in(it was about 80%). This morning my alarm went off fine, and I hit snooze as I normally would... then woke up after 7 to find my phone again locked up(Snooze alarm failed to sound), unresponsive and I had to do a hard reset.