After changing the battery on my 2009 13" MBP unibody, I found that it would not sleep on closing the lid. I did all sorts of first aid. SMC and PRAM resets, HD verify, file permissions repair, clear system caches etc etc, all to no avail. I was beginning to suspect an issue with the new battery. I therefore took off the back and replugged in the original battery, which was down to 75% health but otherwise OK. No improvement resulted so I reconnected the new battery
I then noticed a tiny push in connector alongside the main battery connector to the right, which did not look fully seated. I fully disconnected and reseated it properly. Hey Presto! My MPB now sleeps when I close the lid. This tiny connector is very easy to disturb when you are removing the original battery connector for the first time, as the battery connector is quite stiff. If you have the same symptoms, this is the likely cause.
BTW you really need a #3 tri-wing screwdriver to remove the battery hold down screws. A small straight jewellers screwdriver will do at a pinch.
I then noticed a tiny push in connector alongside the main battery connector to the right, which did not look fully seated. I fully disconnected and reseated it properly. Hey Presto! My MPB now sleeps when I close the lid. This tiny connector is very easy to disturb when you are removing the original battery connector for the first time, as the battery connector is quite stiff. If you have the same symptoms, this is the likely cause.
BTW you really need a #3 tri-wing screwdriver to remove the battery hold down screws. A small straight jewellers screwdriver will do at a pinch.