Hello. Making this post for a buddy of mine. Was having some issues with his mid-2012 Macbook (A1278) 13-inch having boot issues. Hard drive appeared ok. Eventually narrowed it down to the hard drive cable. We disconnected the battery and proceeded to replace the cable, however, upon plugging the battery back in and attempting to boot the machine it would not do anything. No battery indicator, no sounds coming from the machine. It will boot with the power cord plugged in, however, there is no battery indicator in the top of the screen. The fan runs on high and upon unplugging the power cord the machine will die. We went ahead and reformatted and reinstalled OSX with the power cord plugged in. Everything including keyboard lights are functional, but the machine doesn't show there is a battery present. There are no bent pins on the battery connector. I've searched the web over for a remedy. Resetting the SMC appears to do nothing. I've tried every button combination/method and it doesn't seem to do anything. Any thoughts/suggestions are greatly appreciated!