The original main battery has done it's job and with Low Battery Charge message it is time to replace. Should be easy given my automotive first hand experience. In short there is a cable (not a battery cable) that runs parallel to the battery inside the box. It enters into it and exits out in a thick conduit and it is stiff. So stiff that you cannot get to the hold down bracket bolt. So no replacement today! What is this cable and how the heck do you get to the 10mm bolt? Not an impressive design.