How to Enable Bluetooth Without a Mouse
Your Mac doesn't seem to find the Bluetooth mouse. You don't have an old-style mouse with a USB cable at hand. Is there another way to activate Bluetooth (yes, there is)?
Sure there is, although not obvious. You will need a cable-based keyboard, though (USB). Connect the keyboard and invoke Apples desktop search Spotlight. You can do so by pressing first cmd, holding it down, and then the space bar. In case you have changed that key shortcut, use the one you have set for your system. When the Spotlight field appears, type "blue" and hit return on the suggested result "Bluetooth Data Exchange". If Bluetooth is disabled, the data exchange tool will request to enable it. Confirm with return again. You don't need to choose a file to send when the file window pops up, but it doesn't hurt, as the system will still present you with all Bluetooth devices it finds to choose from. At that point, your mouse should have connected. If not, turn it off and on again. (MacConfig)