I hope your Gemini gets better soon Rosie, without the need to get the battery out.
One thing to note that might be interesting to others coming to the thread is that the Gemini battery is replaceable in the sense that it's not soldered directly onto the main board but it's not a removable part such that you can pop the back off and swap an old/used battery for a new one.
The final technical spec on Indiegogo states:
"
We proceeded to look at other solution making the battery replaceable, but not removable in the sense of not requiring any device maintenance.
In the end we decided to create our own custom battery that can fit the space.
The battery is not removable, but is replaceable. Having a removable battery would make the device thicker and we did not want that either. The battery can be replaced, as it plugs in neatly into the side PCB. Replacement batteries will be available.
"