It is a pretty straight forward job.
Once the battery is replaced the windows need to be reset by rolling the windows all the way up. holding up till the motor drops out, do this one more time then roll them all the way down. The front windows need to be done first then the rear. The steering angle sensor will relearn while you drive. All the codes will be stored still in the computers and will need a scan tool to clear them. Colin
This is NOT the question I asked! I wanted the steps to remove the main battery and put in the new one NOT reset the computer!
Okay. The Main battery is the one on the left side. Disconnect the negative battery cable using a 10mm ratchet. Do not unscrew the nut to far as the end of the stud is flared in will cause the nut to get stuck. The Positive battery housing is secured with a 13mm nut. Once loose lift the bottom of the fuse box / positive cable and work it free. Once this is lifted up you can see the vent tube going to the battery, disconnect it. Then at the base of the battery on the wheel well side is the bar that holds the battery down. It is also a 13mm. The bar then lifts to about 45° then it will slide out of the base plate. Slide the battery towards the front of the vehicle and start to lay it on its side by pulling on the handles on top, this is assuming it is a factory battery, then lift the battery at the rear of the vehicle out and bring the battery out on it's side. This is for the correct battery which is a absorbed glass mat battery and not a traditional lead acid battery. The install is reverse of removal. Key points to pay attention to are the tail light, because it is so tight you could damage the light if not careful. If you would like the light is held on with three torx 25 screws and will give more light and space to replace the battery. Also the hold down is difficult to get back into place, if this happens slide the battery side to side in the car this should help the bar slide into the hole. The connector on the fuse / positive battery box can be removed, it is the voltage signal to the front body control module. This will allow you to pull the box further out of the way to better see the hold down. Also there is a plastic strip on the pinch in front of the battery. This just slides up and off, again allowing more room to work. If you need more help please let me know. I am here to answer your question. As I had said the battery is fairly easy the electronics afterwards are the important part. Colin
Also Is this a convertible? There are a few extra steps to be done if it is.
Yes, it is a convertible
For the Convertible there is a quick way and a hard way. The quick way is using a socket with a swivel to remove the fuse box. It is either a 6 triple square or a 30 torx, remove the screw at the top of the rear fuse box. It will be hidden behind a wire harness. Then the fuse box will slide out towards the boot. You will want to remove the tail light. The rest is like every other car. Colin