Leave it to charge for 60Min (if you not yet) then device will automatically turn on...If not try "Hard Reset"
So i let my phone die out, then let it charge it showed the icon that it was charging. Eventually the nokia sign was showing but just froze there so i soft reset let it charge for a few hours and it still wont turn on. Help please
Which phone do you have??
If the battery is removable once the battery might be loose... Happened with me quite a times... Use a paper bit to tighten the battery...
Or hard reset procedure :-
1. Turn off your Lumia .
2. Press Volume DOWN and keep pressing it while you connect the charger until you see an exclamation mark!.
3. Press - in this order - Volume UP - Volume DOWN - POWER - VOLUME DOWN.
4. Your phone will reset and reboot. Pls be patient during the reset process.