after macOS Monterey 12.6.9 update, Bluetooth will not turn on.

Hello tomakechange0,

We're happy to lend a hand to see what we can do to get your Bluetooth working again.

Reading your post it sounds like Bluetooth may be grayed out.

Try restarting your MacBook Air in safe mode following the steps for the processor in your Mac. It's normal for your Mac to boot up slower since it's doing a checks and balances similar to First Aid. Once in safe mode, can you enable Bluetooth? Restart to get back in normal mode, and can you turn on Bluetooth? For safe mode steps, see Use safe mode on your Mac - Apple Support.

Reach back out and provide details of what happens when you try to use the Bluetooth, is it grayed out, or you can't pair a device.

Take care!

tomakechange0,

Thank you for testing in Safe Mode. Restart and check to see if the issue persists.

These steps should help you further isolate the problem:

"If the issue continues in safe mode

If the issue continues in safe mode, the easiest and most likely solution is to reinstall macOS. Reinstalling macOS doesn't remove your personal files, so you can do it whenever you need to.

If the issue doesn't continue in safe mode

Leave safe mode by restarting your Mac normally, then try to reproduce the issue. If the issue doesn't return, it might have been resolved by the other things that safe mode did at startup, such as checking your disk and clearing caches.

If the issue returns, it is caused by a login item or other software that safe mode prevents from loading at startup. In that case, remove login items to find out whether a login item is at fault.

If a login item is not at fault, your user account might contain other software that is incompatible, including certain software that loads at startup. To confirm, you can add a user account in Users & Groups settings, then log in to that account and test again. The new account won't have the same settings as your old account, but you can create those settings again.

If nothing else works, reinstall macOS. Reinstalling macOS doesn't remove your personal files, so you can do it whenever you need to.

If you still can't resolve the issue and need help, please contact Apple Support."

Additional details can be found here: Use safe mode on your Mac

Hopefully this guides you to a resolution.

Cheers!