I think I have a potential simple fix for you. I have an a1200 that I just can't seem to get the drive to line up with the case so the disk doesn't go in quite all the way and behaves just as you complain. Take the top cover off the case and see if it boots in df0: I suspect the drive shifted during shipment and must be fiddled (re-aligned) with to get disks to go in properly. There are two external screws and one internally which hold the drive in place.
