Identifying the Problem

These are instructions for fixing a Seagate 7200.11 hard drive that is stuck in the BSY state.  This can be determined by the fact that it won’t be recognized by the computer’s BIOS.  If your drive is detected, but shows up as a size of 0, then you’re drive has a different problem and these instructions will not apply.
If your Seagate hard drive was bought at retail, then you are lucky.  Seagate will fix your drive for free!  See this Seagate Forum Post for more information about how to contact Seagate Tech Support to have them fix the issue for you.
If your drive is an OEM drive, then you’re probably out of luck.  My drive came with a Dell computer.  It was under warranty, so Dell sent me a replacement hard drive, but they wouldn’t do anything to help with data recovery.  I was stuck with either paying someone to have it done, or doing it myself.  I’m a pretty frugal guy, and the DIY method didn’t sound too intimidating, so I gave it a try and was successful in un-bricking my drive.
These instructions are meant to be fairly comprehensive, with lots of pictures.  After reading through them once, you’ll probably want to refer to the Short & Simple Instructions for fixing your own drive.
I’ve read through a few other web pages to gather this information.  The main one was this MSFN thread.  You need to read through that entire thread to get good information though – the OP has a few things wrong and is corrected by another poster in later posts.
NOTE: I am not an expert.  I’ve gathered these instructions from other places and successfully followed them to repair my own drive.  I do not guarantee that they will work for you.  Proceed at your own risk.

What you will need

You will need some basic soldering tools.  A simple soldering iron and resin-core solder will work fine.
You will also need a Torx T6 screwdriver for removing the hard drive’s PCB.

DAS hab ich gemacht :

… , you could try this USB to UART adapter (ich hab dann bei Conrad zugeschlagen) instead.   The good news is that less soldering should be necessary, since it is powered from the computer’s USB port.  I haven’t tried using one of them, so I can’t guarantee that it will work.  Other people have had luck with random cell phone USB adapters that happened to contain the right type of electronics.  The MSFN thread referenced above contains more information.

Finally, you’ll need various wires and connecters for putting everything together.  I simply made do with what I had lying around, and if you’re the type of DIYer who’s actually considering this project, you’ll probably be able to do the same.

Hardware Preparation

Prepare Drive

Loosen or remove the PCB from the hard drive.  Place cardstock between the PCB and the contacts for the drive head.  Leave the drive motor contacts in place.  Tighten the three screws closest to the motor contacts.  Leave the other three screws loose or removed.

Hier unterbreche ich mal: In meinem Fall war jetzt nix mit “Strom an des RS232 Adapter”. Das USB Teil bekommt Strom vom USB. Ich habe also die 3,3V RX/TX/GND Verbindung nun mit der Platte hergestellt… und es geht weiter…

Terminal Configuration

You will need a terminal program on the computer to which you connect the USB adapter.  You can use Hyperterminal, which comes with Windows XP & earlier.  I suggest using putty, but any terminal program will do.
Configure your terminal program to use the serial port with the following settings:

Baud	38400
Data Bits	8
Stop Bits	1
Parity	none
Flow Control	none

Testing the USB Adapter

Confirm that the USB adapter is connected to the laptop, and the hard drive is not connected to anything.  Turn on the power supply, and start your terminal program.  Type a few letters.  If you see the letters that you type, then you have your terminal program in "local echo" mode.  Turn this feature off, otherwise you’ll see double characters when talking to your hard drive.
Next, create a loopback connection on the adapter.  All you need to do is connect the RX & TX pins of the adapter together.  These pictures show a loopback being created by connecting a wire between the contacts that will eventually connect to the hard drive:

Now if you type into your terminal program, you should see the characters being displayed.  If not, then there’s something wrong with your USB adapter, and you should not proceed until you determine the problem and fix it.

Fixing The Drive

Turn off your power supply.  Connect the USB adapter to the hard drive’s serial pins.

Attach the power supply’s SATA power connector to the hard drive.  Turn on power to the  USB adapter and the hard drive.
NOTE: Commands for you to type are in red boldface.  Pay attention to upper & lower case – it is important.
After a few seconds, Press CTRL+z.  You should then see a prompt like this:
    F3 T>
If not, you may have the TX & RX wires swapped.  Switch them and try again.
Access Level 2 (type /2):
    F3 T>/2 (enter)
    F3 2>
Wait about 20 seconds, then spin down the motor:
    F3 2>Z (enter)
    Spin Down Complete
    Elapsed Time 0.147 msecs
    F3 2>
If you instead see a message similar to this:

    LED: 000000CE  FAddr: 00280D4D
Then you entered the commands too quickly after supplying power to the drive.  Cycle power, wait 20 seconds, then begin again.

Very carefully, remove the cardstock that you placed between the PCB and the drive head contacts.  Carefully replace and tighten the 3 loose screws.  If you removed the screws, I suggest using a small piece of masking tape to help you hold the screws while you put them back in place.
Then start the motor:
    F3 2>U (enter)
    Spin Up Complete
    Elapsed Time 7.093 secs
    F3 2>
Next go to Level 1 (type /1):
    F3 2>/1 (enter)
And do a S.M.A.R.T. erase (create S.M.A.R.T. sector):
    F3 1>N1 (enter)
When the prompt comes back up, turn off power to the hard drive, wait a few seconds, then turn it back on. 

STOP! Wartet auf jeden Fall 60 Sekunden, bevor Ihr wieder einschaltet. DAS IST WICHTIG. Das hat mich 3 graue Haare gekostet. Nach nur ein paar Sekunden reagiert nach dem Poweron die Platte auf jeden Befehl mit einem Error… Wartet man wirklich ca. 60 Sekunden – reagiert die Platte und es kann wirklich weiter gehen!

Wartet Ihr nicht, könnt Ihr Euch evtl. auch bei 30 Grad SO in Denkerpose nach dem Problem suchen sehen, und JA – ich hab ne Hose an…

Wait about 20 seconds, then finally do partition regeneration:
    F3 T>m0,2,2,0,0,0,0,22 (enter)
After 15-30 seconds, you should see something like:
    Max Wr Retries = 00, Max Rd Retries = 00, Max ECC T-Level = 14, Max Certify Rewrite Retries = 00C8
    User Partition Format 10% complete, Zone 00, Pass 00, LBA 00004339, ErrCode 00000080, Elapsed Time 0 mins 05 secs
    User Partition Format Successful – Elapsed Time 0 mins 05 secs
Do not turn off drive until you see this message.
Once seen, drive can be turned off.
Power down everything, place drive back into your computer, and confirm that it’s working.

DAS WAR ES! Sollte wieder laufen, die Möhre!

Bei mir auf dem Tisch sah das Ganze dann so aus:

Ganz nebenbei lief dann noch die Rettung der ein oder anderen Büchse mit Plattenschaden mit: