Last night we had a power failure that lasted about 2-3 hours or
so ...
The noise sounded as if the fan blades were striking something.

You ought to take advantage of the warranty
to assure the defrost timer doesn't need replacement.

I had a similar problem with a frost-free freezer:
the inner coils froze up because the defrost timer had stopped
and the fan was hitting the ice.
A kind neighbor told me to find the timer on the bottom back corner
of the fridge. Since it was a good 'old mechanical timer like a clock motor,
a twist and shake got it running again.