Another success! I unbricked my Seagate Barracuda (500 GB)! I used the following things: - a laptop running Win XP - a deskop PC (running Win 7) - a "USB to TTL Serial Cable (3.3V)" (TTL-232R-3V3-WE) (FTDIChip.com) Instead of dismounting the PCB, I used the technique of covering the connection under the PCB at the left side of the drive (having the hard drive's SATA port in front of me with the PCB on top) with some piece of plastic. I powered the drive with a standard Molex-SATA power adapter using the desktop PC. NO additional powering (battery etc.) was necessary. For the hyperterminal interaction, I used the laptop with Win XP. First of all, I simply plugged in the USB side of the TTL-232R-3V3-WE cable (without having the Barracuda connected). Win XP recognized the new hardware. I installed the drivers taken from the FTDIChip.com website with the "Have disk"-button. Then I followed Gradius' method found in the first post in this thread. After that I rescued my data and installed a new version of the Seagate firmware.