Before you start:
Make sure your phone supports USB On-The-Go (OTG). Especially some of the cheaper ones don’t. In some cases, you might need to dig deep into the technical data of your phone OR you may need to download an App to check (for example: USB OTG Checker). Your phone needs to have at least Android 5.0 (Lollipop) running. Some phones might face problems when the Tentacle battery is almost empty. Charge the Tentacle at least a bit to avoid that problem. You then need the the Setup Cable for Android (OTG) that comes with your Tentacle, and you need to use it together with a Micro-USB cable. Be careful when you plug it in: Both ends look the same. Be sure to connect the OTG end of the cables with your phone.
Still not working?
Try to restart your phone. Sometimes that helps.
Android with USB-C connector:
If you have an Android Phone that has a USB-C connector, you basically have to use the same setup described above, but instead of the provided OTG cable, you will have to get an OTG cable with USB-C instead of Micro USB.