Most notably we had a large NetApp array that would not boot, once we replaced the controllers we had lost 13 out of the 60 hard drives in the array. They would no longer spin up. Like physically seized. Because they had been spinning for so long, they would have likely kept spinning just fine, but with power gone, it was done.
Fans are another fun one, anything with ball bearings really. Power supplies are another issue, due to the sudden large inrush of power when the switch was flipped back to on, some power supplies had their capacitors go up in smoke.
This is not rare, this a common occurrence. When you have an absolutely massive footprint with thousands upon thousands of servers, that have been running for a long time, there will be things that just don't come back once they have stopped running or when the electricity is gone.