Chosen Solution
The battery checker switch is likely not popping back so its always pressed. What you’ll want to do is remove the battery and on the side carefully remove the two screws holding the checker module. Once out you can clean the button and make sure its not corroded up, as the LEDs to the left should be lit. You might need to replace the module. MacBook Pro 15" Unibody Late 2011 Battery Replacement Lets also get a better view on what’s happening here install this gem of an app CoconutBattery take a snapshot and post it here for us see Adding images to an existing question
