Original post by: Max Tech ,
i think the fans running at full speed can be caused by a broken palm rest temperature sensor. as far as i know, when the system detects one of the temperature sensors doesn't work, it makes the fans run full speed (that's at least what happened with my iMac when i broke the hard drive temperature sensor. You might've either damaged the sensor or the cable during the removal of the old battery. I don't know how to replace that palm rest sensor though.