bluetooth can't turn on after upgrade to Monterey 12.1

Howdy vnyi,

It sounds like your Bluetooth isn’t working correctly on your computer. We know how important having a working Bluetooth feature is for you, and we will help get you to the right place to find a resolution.

Have you tried a normal restart of the computer? This simple step can resolve issues like this.

• Shut down or restart your Mac.

Another troubleshooting tip that you can apply is to hold option + shift keys on your keyboard and click the Bluetooth icon in the menu bar. However, Not all Mac models have this option. But this brings up a hidden menu that includes a Reset the Bluetooth module option. Use it and let us know if it fixes the Bluetooth issue!

Take Care!

Any Third Party Applications that will interfere with the normal operation of the OS, alter, modify, remove or delete or attempt to do so is an invitation for disaster and may require a Reinstallation of the OS.

This includes AntiVirus, Disk Cleaners, Disk Optimizes, UnInstaller etc.

If any of the above types of applications have been installed and used on the computer - they may have corrupted, remove etc aspects of the OS and thusly may required Reinstallation.

The The Built in Security  is all that is required.

Try booting mac into safe mode, and try turning on bluetooth(if possible). Click on the link below to know how to get into safe mode.

How to use safe mode on your Mac - Apple Support