Another person here with just a board attached and no drive at all (leaving room for a 3.5" HDD upgrade soon).
I'd check the connections on the logic board and motherboard, make sure everything's snug. Even if it looks right it might have moved since you put it together. I've successfully updated then straight away tried another and it got locked into the update loop, adjusting the cable fixed the problem.
Your results are saying the board isn't communicating with the PS3, so it's either not connected properly or it's dead. Since it worked to get you out of the update, it must be loose.
Are the clips that hold the silver ribbon cable still there? They break fairly easy and unless you're used to it, they can be awkward to fix 100%. I cut up plastic milk bottles and use that as a shim, just scrape one edge with a knife to give it a diagonal edge to slide into place and careful not to damage the pins (if you're going that route).
oralphie: Will this allow chuck norris to play backups??? PLZ HELP!!!