gallerygolfer Said:
"My MacBook Air cursor is locked in the upper left corner at login. Keyboard in unresponsive. Bluetooth Setup Assistant is spinning endlessly. How do I proceed?"
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Reset the Bluetooth Module:
Go Here: Use "Reset the Bluetooth module" to Fix Constant Bluetooth Disconnections - User Tips.
Perform this in Safe Mode:
When you boot into Safe Mode, items load by default, with all settings and caches set aside. So, hold down the shift key upon boot. Once booted into it, reset the Bluetooth Module, restart the Mac, seeing what happens, such as if it is still stuck. While in Safe Mode, damaged system files (i.e. caches) are reset.