Thanks for your reply, but the number shown when you use the info option is the Hardware ID#, which is totally different from the manufacturer's serial number. If this is the number saved with each backup, then I'm afraid that won't do me any good either.
Ok, you mean the barcode sticker on the back of the TH55.
This number as far as I know is not stored in ROM.
Well, the number printed on the mentioned sticker is printed on the barcode sticker of the original box too. The barcode sitcker of the box has a number that begins with S01-xxxxxxx-B the xxxxxxx is the serial number.