One minute my Kyocera phone was just fine, and the next it was dark and wouldn't start. The battery was not discharged.
I tried the on/off button, that same button with the volume down button, went on youtube and found a suggestion to hold the buttons along with plugging in the charger at the same time.. nothing worked.
The Verizon site suggested using a computer as a 'trickle charger' instead of the regular charger. And bingo, that worked!
I noticed that lately when on the wireless charger the phone would keep disconnecting and reconnecting to that. Strange.
Anyway, just passing this along in case you have trouble.
"If I'm wearing long pants, I'm too far north" - 2oldman