How to reset Android Tablet Lenovo with pc?

Today somehow the tablet turned black and after few minutes pressing random button, I saw the screen showed " Now send the package you want to apply to the device with "abd sideload "... I tried to reset it by hitting the reset button, volume button, trying take out the battery but no luck. Im first year in college and learned little bit java so I just downloaded the andriod studio to have the adb in order to reset the table. I am not sure how to do it to be honest.. Thank you for all advicesThis is Leveno Tablet tab a8