When you connect a battery to the units, you will be able to join a wifi network called iSpindel after about 10-15 seconds, maybe longer. Once you join the network, depending on your device, you will either be taken to the configuration page automatically. If not, you can go to
http://192.168.4.1 and configure the device. The process is documented on the Github project page:
https://github.com/universam1/iSpindel/blob/master/docs/README_en.md#portal
You will need to trim the pins on the sleds to they fit snug without going crazy, inside the bottle. Only place the PCB in a small way, enough so that the lid can be secured correctly, then place in tap water. The aim is the get to 25 degrees tilt via the webui however +/- 4 degrees should be okay. The further the PCB is the lower the tilt, for example; you may start at 45 degrees however tapping it in slightly more will see you get closer to 25.
You can calibrate them easily enough by ensuring the tilt angle is known in water, then also known in your wort before fermentation. This will give you a good indication of the fermentation process. You can fine tune them with water with dissolved sugars to take additional points, this will give you a nicer curve and a more true reading during fermentation.
The full calibration procedure is provided via the GitHub project as well:
https://github.com/universam1/iSpindel/blob/master/docs/Calibration_en.md