Brushes stopped working? Problem with the coil/stator? Lots of potential problems that can fail an alternator. Always remember, stuff was working before it broke.
At some point X it stopped working and with electrical stuff, it's often "digital" works/doesn't work.
I went out to use the back bathroom at our house the other night and the light switch didn't work. Brand new switch less than 2 years old and it just crapped out when I hit it.
If you want a junker alternator for parts let me know. I just took one off our 06 because of the decoupler pulley so I have a spare with 75k miles on it that works fine.