If it was me I'd call Sony telling them I got it back that way, and ask how to get out of the mode if hardware isn't required to do so... rather than sell it.
It was also on ebay in early march and didnt sell because the buyer didnt pay. I didnt catch it that time around but seen it this time.
It was accidently sent back to the end user like this from sony after it was sent in for a bd drive repair.
They got the run around from customer support so it ended up on ebay, so they did try the route you mentioned PS3News.
It is unknown if they tried to do a fw update to get out of it. and one of the things i would like to know is if a "retail update.pup" will give the "unsupported data" error or not.
Too bad they didnt send it back with a disc in the drive or a ms in the card reader.
On my 60gb the ms light blinks once upon powering up unit before nand is accessed. It is likely the unit is checking for some special file used internally to get the ps3 in this sort of mode.