Hi and thank you for your question. My name is ***** ***** I will be happy to assist you.
How old is the device?
The rest you performed was it a master reset?
OK, when you performed the master reset, did you have the unit plugged into a power source?
Did you try using a different power source? For example, using the computer to charge it vice the AC power adapter?
Also these models have known issues with the power button. Try pushing the power button with more force than is usually used.
What is the hard reset method you used?
Alright. One last thing you can try is cleaning the contacts where the charger attaches to the devices and the contacts on the charger as well to make sure the device is getting a charge. You can clean the contacts using isopropyl alcohol. Once the contacts are cleaned, connect it to the charger again and allow it to charge about 30 minutes before trying to turn it on again.
Alright, then I am afraid there is something internally wrong with the device. You have already done all the troubleshooting procedures to try and revive the device and it is not turning off. The device is out of warranty but you may still be able to send it in for repair. I am out of ideas. I will opt out and let other experts look in in case there is something I missed though.