1. Don't worry about the other thread, I deleted it
2. Try a long press on the power button - up to 60 seconds until it boots
3. Or try a cold boot - linked below
4. Try charging from your PC or other 500mah usb charger overnight, before trying again (there's a thread that explains why, linked from FAQ & help)
5. Try connecting to a tv via hdmi to check it isn't the screen that's not working. If it is the screen you should Factory Reset to protect your privacy & then return it.
If none of that works, then you will have to return it.
Hope one of them works for you