I think I know the problem - The battery is a CR2032-HE2
So it's got solder tabs (and not even owning a soldering iron - that's put pay to changing that)... I thought it would just slide in / out - but no....
I have the exact same problem.. Is there an idiots guide to replacing the battery on my Trinity Pro? I've tried on a number of occassions to remove the back / bottom - but I'm clearly missing either screws or something else as I've never managed to free it up enough without some resistance to ...