These instructions should get you from a Bricked Sheeva/Dream/Guru/OpenRD to getting uboot running in Ram ready to restore your system from USB/TFTP.
I am assuming you are using a Linux PC to run Openocd.
Firstly install the packages required.
sudo apt-get install openocd telnet screen
Connect & Power up your device with the mini usb cable and jtag(Dreamplug & Guruplug).
Open a terminal session and connect to the plug console.
screen /dev/ttyUSB0 115200
Open a 2nd terminal session.
Select one of these for your device.
Marvell u-boot
wget http://www.downloadsnewit.co.uk/u-boot/recovery/sheevaplug/u-boot.elf
wget http://www.downloadsnewit.co.uk/u-boot/recovery/dreamplug/u-boot.elf
DENX u-boot
wget http://www.downloadsnewit.co.uk/u-boot/recovery/sheevaplug/denx/u-boot.elf
wget http://www.downloadsnewit.co.uk/u-boot/recovery/dreamplug/denx/u-boot.elf
wget http://www.downloadsnewit.co.uk/u-boot/recovery/guruplug/denx/u-boot.elf
wget http://www.downloadsnewit.co.uk/u-boot/recovery/openrd/denx/u-boot.elf
For Sheevaplug/ Dreamplug / Guruplug
sudo openocd -f /usr/share/openocd/scripts/board/sheevaplug.cfg -s /usr/share/openocd/scripts
For OpenRD
sudo openocd -f /usr/share/openocd/scripts/board/openrd.cfg -s /usr/share/openocd/scripts
You should see output similar to this.
Open On-Chip Debugger 0.4.0 (2010-10-08-15:52)
Licensed under GNU GPL v2
For bug reports, read
http://openocd.berlios.de/doc/doxygen/bugs.html2000 kHz
trst_and_srst separate srst_gates_jtag trst_push_pull srst_open_drain
jtag_nsrst_delay: 200
jtag_ntrst_delay: 200
dcc downloads are enabled
Warn : use 'feroceon.cpu' as target identifier, not '0'
Info : clock speed 2000 kHz
Info : JTAG tap: feroceon.cpu tap/device found: 0x20a023d3 (mfg: 0x1e9, part: 0x0a02, ver: 0x2)
Info : Embedded ICE version 0
Info : feroceon.cpu: hardware has 1 breakpoint/watchpoint unit
If you are using a jtag and getting errors at this point replug or even swap jtag cables and retry.
Next open a 3rd terminal session.
telnet localhost 4444
Output should look like this.
$ telnet localhost 4444
Trying ::1...
Trying 127.0.0.1...
Connected to localhost.
Escape character is '^]'.
Open On-Chip Debugger
>
For the Sheevaplug / Dreamplug / Guruplug
reset;sheevaplug_init;load_image u-boot.elf;resume 0x00600000
For the OpenRD
reset;openrd_init;load_image u-boot.elf;resume 0x00600000
Now you should see Uboot starting to run in the 1st terminal session and you are ready to start restoring your plug.