I just got done talking to Apple Support about this and they got mine working again without me having to swap out (again). First - go into your phones Bluetooth section and forget your headphone device. After I reset mine,for some reason, freaked my phone out and would try searching for the headphones - even though they were on,etc - it will just save you a headache later. Instead of doing the "regular" reboot of 10 seconds - hold down the power and the volume down button for 20 seconds. Your headphones should go from a solid red to blinking red/white and then off. You should be able to start your headphones and reconnect to your phone after this.
I asked why the 20 seconds and not the 10 - apple support just said it was another way to reboot the headphones. Not sure why they don't let people know of the different ways to reset.
I had read somewhere that the powerbeats2 battery problems were caused by water/sweat coming into contact and causing corrosion - so for the powerbeats3 they built this "protection" that has an auto off feature to protect the battery - so that could be why it won't turn back on without a reset - its basically powering down to protect itself...I guess.
Hopefully this helps! I've also wrapped my microphone with cellophane and electrical tape to help with the water/sweat getting into the headphones - I'm hoping this will help