Hi there and welcome
Can you remove the power cable
Then hold the power button for 60 seconds then release
Connect the power cable and tell me if it then starts please.
Ok, hold the volume UP and Power buttons for 6 seconds and release with the charger connected
Does it then start.
It is the internal mainboard that has faulted, this now confirms it.
I am really sorry about this and you are going to have to return the tablet to have it replaced. It will be covered by the warranty if this has not expired, and the replacement will be done at no cost to you.
I am really sorry about this, and if you have problems, or would like any additional information or assistance, please do not hesitate to let me know.
And if you can take a second to rate my service by clicking one of the stars at the top of the page, then submit, that would be greatly appreciated.