A Western Digital firmware update issue goes very wrong on a Mac Mini

I just got off the phone with a client who has a Mac Mini and four external hard drives. Three Western Digital and one Seagate. Based on our brief conversation it sound like one of the Western Digital MyBook drives might have had an issue which triggered an unfortunate series of events. I frequently see problems in the shop with these WD MyBook drive cases.
He thought the firmware might need to be updated on the Western Digital drive. (I was not aware that WD had firmware update the you could even run on a Mac.) I’m a little unclear on the details, but he ran the firmware update with just the problematic drive plugged in, as the instructions directed him to do. Something went wrong and he was able to see his data for a moment, so he started copying as much as he could off to the Mac Mini. He ran out of space so he plugged in the chain of (2) other Western Digital and (1) Seagate hard drives as more places to copy data to. When he plugged them in they all came up with a “MyBook” drive icon (including the Seagate) and all three of them had zero items on them. (they had been full of data) Now when he plugs any of them into a Mac laptop or the Mac Mini they all have nothing on them and all have the new WD icon (including the Seagate drive).
I don’t have all the details, and I’ve not seen the case yet (he’ll be in on Monday), but I thought this was strange enough to put up a warning against running the Western Digital firmware update.
I’ll post more details when I have them.
11/25/08 – I started trying to unravel the details of this totally crazy case. It does appear that whatever happened with the first WD hard drive in question did damage data. The drive is blank, but after scanning the drive, we are pulling data off of it via data recovery. I still have no clue on what happened. We have yet to look at the remaining three hard drives, that the client reports are in the same boat.