I have Mid 2012 MBP Retina. I have had the display and the logic board replaced both at no charge by Apple because of display issues. Periodically, the screen will go dark usually when it is less than 35% battery and will indicate that the battery needs to be charged. The percent charged amount will jump around as well. It is at about 1200 charges so indicates that the battery should be changed. Could something besides the battery be the issue? Additionally, is it good value to change the battery on a well used computer of this vintage or better to get a new one?