My MacBook also wont turn on after fully charged

Let’s give this a try follow this guide MacBook Pro 13" Unibody Mid 2012 Battery Replacement to disconnect the Battery. Then with nothing plugged in press and hold the power button for a good 15 sec’s so you fully discharge your logic board. Now carefully plug in your MagSafe cable. Did the system spontaneously start? What happens when you press the power button?

Now shutdown your system and plug the battery back in and try to restart the system once more with the battery only. did it start up?

Let us know what happened