I would suggest contacting AOpen support if they dont have a utility for reflashing the drive you should at least be able to obtain info on how to do it.
EDIT: if you cant get help from AOpen you can try and recover the drive your self. download the right firmware ( if you have a Pro it would be 1.02) you can extract the AOpen flash utility( AO flash.exe) and the firmware .bin file from it with winrar. then you need a Win ME boot floppy you can get it here.http://pioneerdvd.rpc1.org/#BOOTISO
you can use the Floppy image or the CD ISO then scroll down to the Firmware flashing FAQ in FAQ/How To's and study how to create the boot floopy or disk you need and how to use it.