The following procedure solved my issue:
How To Fix “Bluetooth Not Available” Error
Note: Following this guide will reset your bluetooth module and all connected devices will be inaccessible. If you rely on a bluetooth keyboard, find one with a cable before you follow these steps.
Bluetooth remove plist OS X System Library Steps How To
Open Finder (furthest icon to the left in your Mac’s Dock)
While holding Alt (Option), click Go in the menu bar (A). This unhides the “Library” menu option.
Select Library from the list (B). The folder will open in a Finder window.
Navigate to the folder Preferences and find the file com.apple.Bluetooth.plist.
Delete the file. You may be asked to type in your Administrator password to do this.
Lastly, shut down your computer, wait a few seconds just to be sure, and then start it back up again.
Your Bluetooth should now be working like before!