If your Bluetooth device is still not showing up you might want reboot your Mac in safe mode. You can do this by:
- pressing and holding the power button on your Mac until “Loading startup options” appears.
- Select a volume. Press and hold the Shift key, then click “Continue in Safe Mode”
- Restart Your Mac normally.
If this still doesn’t work, it’s probably best to take it in. Or you could reinstall your OS, which is a really big pain, which is why it’s better to just take it in to see what’s really going on.