Re: Informal poll on whether you've ever had to do something like this
No so much Resurrection as Resuscitation.
In the dim and distant past I did a stint as a support bod at a large London investment bank.
As part of their BC/DR processes we were scheduled to come in over a weekend to carry out a controlled power down of the data center under simulated outage conditions. Building power isolated, Switch to generator power, fail over to the remote DC somewhere in Hertfordshire, onto battery backup (they had an entire sub-basement full of lead acid battery's on heavy duty racking) and then gracefully power everything down before bringing building power back online, recovering the DC and re-connecting to the remote DC to resync everything.
All went well with the shut down, UPS took the load as the building power was cut. Generators came on line and ran for an hour before being shut down again and leaving the building on battery power while we ran through the shutdown routine for the DC.
The problem came when we started powering the kit back up. Most of the servers came back just fine
but the rows of cabinets containing a couple of hundred IBM PS/2's performing non-essential (i.e. not trading floor related) tasks remained ominously quiet. Turned out the last time they were shut down was 3 years previously during the last test, and 90% of them had failed to boot due to stiction. Cue myself and 2 other support staff armed with rubber mallets from the FM stores working our way up and down the aisles, pulling servers from the cabinets, opening the cases, whacking the drives a couple of times and replacing them back in the racks to see if they would boot. We got them all back eventually but it was a lot more overtime than had been planned for.