bluetooth just spins won't. connect

See >>> If you can't connect a Bluetooth accessory to your iPhone, iPad, or iPod touch - Apple Support

Ensure that your Bluetooth accessory is itself in “pairing mode”. Refer to your accessories’ product manual for guidance, or contact the manufacturer’s technical support team for assistance.

If you already tried (to no avail) ALL the steps provided in the support article that led you here, AND if your device can connect a different BT accessory, I suggest that you contact your BT accessory manufacturer support team and explain your problem.

Regards

Giulio