MBP Battery normal but won't charge, pro is now glitchy and slow
Your battery is dead.  

I’ve written a short guide to diagnosing a battery problem which you’ve already done.  A battery charging or not won’t have anything to do with the OS installed, how much space you have or even if there’s a virus. Remember, your battery will charge when the machine is off.  So, while checking that info doesn’t hurt, it’s not going to help solve the issue.

There’s one other thing and that’s to check the charger itself.

For more info see the following posts:


Mid 2012 MBP shuts down claiming no power with charge at 30% or 40% or more
Can a low-wattage adapter fully recharge the battery of a turned off MacBook?
3rd Gen Macbook pro randomly suspends


One last thing you can try is to disconnect the battery and try to run your Mac. Yes, you won’t be able to disconnect your charger, but it will help you diagnose the battery issue by removing it from the equation.