Does the serpentine belt breaking cause an alternator to go bad or vice versa?

Just the other week I had the power steering pump and serpentine belt replaced on my '96 Ford Taurus; since then my car started making some grinding noises particularly when I was idle (The car drove completely ok with the exception of the noise) -- After doing some research on the net I found that its a good possibility that the alternator's bearrings went bad. Do you think this caused my serpentine belt to break the other week? Or do you think that the serpentine belt breaking caused the alternator to go bad?

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