You're going to have to do some more digging to figure out exactly *which* devices got reconfigured or misconfigured.
I've seen a couple of different "we powered down and everything went pear-shaped" events.
One was with MCCs with the original generation of E3+ overload relays. The DeviceNet address and data rate on those was set via software rather than a dial switch, but it (and several of the important configuration parameters) didn't take effect until power was cycled. Somebody thought they were being helpful by doing a "Download All" during commissioning, which was all fine and dandy until power was cycled and all the overload relays started up with the default parameters in them, and all addressed to Node 63.
Others have included the "Automatic Device Replacement" feature, where the configuration parameters for slave devices are stored with the Scanlist in the Scanner. Folks would save the Scanlist and all the ADR-related data *before* they commissioned and configured the system. On the next power cycle, weeks or months later, the Scanner dutifully over-wrote the active configuration with the stored one.
And in at least one circumstance, the Scanner was found to have been set back to defaults. Turns out the shutdown included quite a bit of welding on the machine frame, and it's so much trouble to actually move the ground clamp......