I was doing some electrical work in the house. I managed to brick my Drobo S the other day when I cut the power from the breaker panel without shutting down the unit. I cycled it a few times in the space of a few minutes and the Drobo wouldn't boot. After buying a support plan ($250) they kindly replaced it. The data was fine and just swapping the drives into the new box worked fine, but it was a bit scary.
Lesson here: plug your Drobo into a UPS. And don't cut the power without a proper shutdown.