tablet wont turn on

This was used for 6 mths and has sit for 3 1/2 yrs. I have connected the mini USB to charging cable that works fine on my phone. Nothing happens, no green light, no anything and it does nothing when power button is pushed for up to 30 seconds. It came with an external keyboard. Does it need to...

The problem here is that i cant access anything at all, and its stuck on loading screen. and since i have a samsung Galaxy SM T560 , i dont know how to open the back and pull the battery out. Is it bricked? or is there Any way to do a hard reset while on loading screen?

what do I do if the screen is bad? My tablet sounds when u push the volume buttons but the screen is black no matter what I pressed volume+power and nothing, I unplugged and plugged the battery, nothing. literally, nothing helps. Somone please help.