Adjust the seat forward and up all the way, remove the push pin plastic rivet
and slide the vent to the right and up out of the way, removed that long cover over the battery by lifting and pulling rearward, then remove the battery hold down bracket a 13 mm socket is needed, then disconnect the negative battery cable , then use a 10mm socket on a long extension and remove the positive cable from the battery, then you can lift the battery out
I use a large pair of visegrips and clamp it to the negative post and heave ho, tilt it out , it weighs about 45 lbs you do not need to remove the seat, cutting the carpet is part of replacing battery, its no fun