This product is now discontinued, but there are a number of them that are still going.  The batteries only last a few years, but are fairly easy to replace.  The plastic case eventually started breaking on mine, which is why I finally discarded it when the battery died for the final time.  I share this information for those who still have theirs in service, and want to replace the battery.

Remove all the hex head screws in the orange outer frame, on both sides.

Once both halves of the orange frame are removed, a number of phillips head screws exposed.  Remove all those too.  The only screws that didn't need to be removed were the feet.  Learned that after the fact.

It pull apart easily, and the large battery is easy to get to.  Other than the electrical connections, nothing else needs to be removed to pull the battery.

Think this was the culprit.  The green/yellow ground wire had rotted off ther terminal.

A new ring terminal was installed.

The terminals on the cables were cleaned with a Dremel moto-tool and a wire brush.  The thin foam padding was pulled from the old battery, a little spray adhesive applied, then adhered to the front/back of the new battery.  It was then set into place.  All the terminals were connected using new hardware that came with the replacement battery.

I had charged the battery prior to installation but verified all the functions of the power pack, including the inverter, radio, etc.

All cleaned up and ready for several years more use.