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

Android 7.0 Nougat: The stand-out features of this new version's android app development includes

Android 7.0 Nougat is the latest version operating system released by Google for portable devices like mobile phones, tablets, phablets and smart watches. The stand-out features of this new version's android app development include:

• Split screen display mode to run two apps side-by-side.
• Multi-window mode
• Seamless automatic system updates
• Bundled single-app notifications.
• New data saver toggle.
• Adjustable keyboard.
• Open-JDK based Java environment.
• Vulkan Graphics support for rendering API.

Google’s operating system is totally acceptable by every end-user for it’s highly flexible functional features and for it’s friendly user version names.