Tablets will not turn on after sitting idle for a year

[Jason254]

Tablets will not turn on even though charged up. I plug in the cable and the battery capacity shows up as a percent (currently 86%) then goes away. I've tried the power on button for ages as well as the power on and +Vol at the same time. Nothing. Not sure if I should replace the battery and see if that helps? Both my tablets have the same issue. I only use them about once a year on trips for maps

[WAWood]

According to the specs I could find, these tablets came out in 2015.  I have gone through two Android tablets in the same time frame.  These don't seem to last very long,  And if the forced reset, which you are doing correctly, does not work, then basically it is a dead slab.  You can try replacing the battery, but I would not hold out hope that will fix it.