These are instructions for fixing a Seagate 7200.11 drive stuck in BSY state.
That is, for a drive that is not detected by the BIOS.
A drive that is detected, but shows up as size 0, has a different problem and requires different instructions.

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.

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.

Connect a power supply to the hard drive PCB, but do not yet turn it on.

Prepare RS232-to-TTL Adapter

I used this adapter with great success.  Only $4 shipped.

Connect the RS232-to-TTL adapter to your computer's serial port.  This is the computer you will be using as a terminal to communicate with the hard drive.

Connect the RS232-to-TTL adapter to the hard drive's jumper block.  You will be connecting two wires: receive & transmit for the serial connection.

Connect power to adapter - use +3.3v from the same power supply you will use to power the hard drive (orange wire is 3.3v, black is ground), or a 3V battery.  If using a battery, connect the adapter's ground pin to the hard drive ground pin.

Terminal Configuration

You will need a terminal program.  You can use Hyperterminal, which comes with Windows XP & earlier.  I suggest using putty.

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

Fixing The Drive

NOTE: Commands for you to type are in red boldface.  Pay attention to upper & lower case - it is important.
Turn on power to the RS232-to-TTL adapter and the hard drive.
After a few seconds, Press CTRL+z.  You should then see a prompt like this:

    F3 T>

If not, swap TX & RX wires.
Access Level 2 (type /2):

    F3 T>/2 (enter)
    F3 2>

Then spin down the (disconnected) motor:

    F3 2>Z (enter)

    Spin Down Complete
    Elapsed Time 0.147 msecs
    F3 2>

Very carefully, remove the cardstock that you placed between the PCB and the drive head contacts.  Carefully replace and tighten the 3 loose 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)

Cycle power to the drive, then 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.