[Blink]

You can try to find a vulnerability in the Android bluetooth stack, or in the bluetooth standard in general. If you find one, then you can try to use it to exploit the device. However, if no vulnerabilities are present, there isn't much you can do.

There are likely variations per device with this, so see if you can find a common bluetooth driver used by many Android devices that is alse open source.
After you've found one, look through the code and see if you can find any vulnerabilities. Rinse and repeat