Tiến Nguyễn: Your device is in the deep charge mode, possibly because it was left running for a long time without charge. Leave it in the charger for 90 minutes, unplug from charger for a few minutes, repeat another charge for 90 minutes. It will get out of the deep charge mode and work again. Use the original charger helps, I think.
Dr Bennett Frankel: Hold power button for 30sec after charge then quick press of button to start. This is a common problem
Charles Hernandez: Update: oddly enough I plugged the USB to the wall and it immediately started to charge. It won't charge with an adapter. I'll do another update once it's fully charged. Thanks all for your responses :)