I have a Macbook Pro Retina Mid 2012 and I replaced the battery. After putting everything back together and verifying all items were plugged back in I charged the laptop backup. Upon pressing the power button, I get no chimes, and no screen. Its just black. The fans do start when the power button is pressed, the Caps Lock does work on the laptop as well. I dont have an external screen to test with so that makes it hard. I have tried a few resets including a SMC reset. Nothing seems to work.