Don't know what that is -> "holding down the buttons and pressing the n twice".
But if I had this problem I would...
Hold down the power button for >10 seconds as this completely turns off the device, then attempt to turn it back on.
And if that failed to work... let it sit and run out of battery, then plug it in to the wall usb adapter, let it charge for an hour, then try powering it on with the power button.
And if that failed to work, since its outta warranty, buy something that works.
But that's only what I would do
Moto G 4G | latest official rom 4.4.4NEW (Longest recorded uptime: 503 hours with 4.4.3)
Nook HD+ 32 | cm11 emmc official rom (331 hours is about the most I can get before forced reboot or other.)