I experienced the same symptoms 2 days ago.
I noticed that the PE was very hot at the time. Few moments before, I was listening music with bluetooth headset, while browsing through wifi. I put the PE in its sleeve, battery was approx 50%. 1 hour later, it was drained out with the blinmking red led. I thought maybe it was due to some background apps (the music player maybe ? ) in addition to the BT + Wifi on ...

Since I rebooted it , it works fine, almost 12 hours battery time ...