bluetooth

Do all bluetooth devices not work, i.e. mouse and keyboard?

Have you tried them with another Mac to see if it's the Mac or the devices that are bonkers?

If your keyboard is a rechargeable battery type connect it with its charging cable and it will work like a wired keyboard.

You'll need a wired mouse and keyboard to try to try to fix the bluetooth in the following order as needed:

1 - How to reset the SMC of your Mac - Apple Support

2 - How to reset the SMC of your Mac - Apple Support

3 - boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following; 

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts 

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

And don't forget to turn both devices on by the switch on the back (keyboard) and bottom (mouse).