Once you have removed all the screws, carefully unplug the battery cable from the motherboard using the plastic pry tool.

Be very careful here as there are other cables that you need to slide out from under. The battery flexes in the middle to make it easier to remove, just go slow and ease it out gently.

Finally slide in the new battery taking care again as before to slide it under the exposed cables. Secure the screw(s) from earlier.