I've tried to open it up but it's potted (epoxied) in there from where I got to.
If it's not working you can send it to Davis for refurb instead of having to buy a new one.
If you feel it's because of how you connected the RJ jack, if you don't have a telephone crimping tool I'd suggest one.
I also noticed on mine I was having intermittent reporting issues where it would drop out for a few seconds to 30+ minutes, turned out to be a power issue.