Dead phone was using the phone and suddenly it stopped and went dead. can't get any power to it at all.

I know this sometimes happens with these smart phones; one day they just up and quit.
You could try a fresh battery, and check your charging source.
Mine did something similar a couple days ago - I thought it was charging all night long, and in the morning when I went to turn it on... nothing. It ended up being my charging cable, it wasn't putting any juice to the phone.