I had the same problem this morning. Ipsmagic was never installed, no headset connected. No charger connected and battery at about 15% with automatic power save mode.

Device was upside down, alarm sound for about 1 second, then it got "snoozed". It started ringing again 10 min later, at which point it worked properly until I shut it off I didn't touch device during these 10 min. Never happened to me before, but usually i have device with front side up during the night and charging.