How to recover a bricked plug from u-boot?

[plugcrazy]

Hi,

I have a bricked plug (well the root password is lost actually). I can get into the serial console and get to the Marvell>> prompt . I did this by I did this by PUTTYing into the plug (teraterm sucks!) and using a pin to do a hard-reset (on the reset pin-hole above the sdcard slot).

What do I do next? I would like to just load the factory default image and load that image. Can I load the factory image using the serial console and then reset the device? Dont know how all that works.

Thanks,
PC.

[rickyleeb]

Hi,

Is the root file system running off nand/SD/USB ? Because if its running of either SD or USB there is not need to reflash. You could use a linux distro (Live cd or usb if you run windows as your native OS) to mount the SD/USB then make changes to /etc/passwd and /etc/shadow to blank out the password.

As for loading a clean image on to the device that can be done with the installer that came on the cd.

[fragfutter]

if you can get into the serial console, you can recover the root password.

You stop the boot process at the u-boot (marvell) prompt. Then you need to modify the boot sequence so that it will not start a normal system but boot /bin/sh as the init process. This will allow you to change the password and reboot.

It has been posted here http://plugcomputer.org/plugforum/index.php?topic=986.0

If you have trouble with this, you should post the output of printenv

[Loattejak]

Well guys I just got this sorted there now. Heres what I did:

Basically, I had to boot into Ubuntu, and install grub from there. To do this, in the Terminal, type:

[hausschuh]

Ok, I was going to post this as a question or "HELP ME". But I fixed it. Since I already wrote down all the problems I had I will post them anyway for all the other poor guys in my situation as a reference.


-------------
I was going to install Debian on my SD Card using the tutorial from tbm (cyrius.com).
I checked which u-boot version I had and since it was too old I had to upgrade it. I used the "USB stick method" from the same site using WinXP.
Somehow this went terribly wrong. I guess the USB Stick was faulty (although it was recognized). So the Sheevaplug won't boot up and I had no access via the serial port (the screen stayed black after pressing Enter several times). The green LED was on, the blue LED was off.

So I read this tutorial to "unbrick" it: http://plugcomputer.org/plugwiki/index.php/SheevaPlug_Installer
I'm not using minicom so the "bug" section does not apply for me.
It seems my plug is older than July so I had no problems recognizing it, I also skipped the section.
I used a brand new USB Stick from Transcend to make sure this time nothing goes wrong because of the USB Stick. I have copied all the files to the root as told in the tutorial and put it in the Sheevaplug. I started it and on XP I ran: runme.exe nand from the command prompt.
After some command action the important lines should be:
successfully erased blocks 5 to 6 and NAND flash[...]
wrote file uboot-dev.bin to NAND flash 0 up to offset 0x000c0000 in 20s.
...
...
...
successfully erased blocks 0 to 4 and NAND flash[...]
wrote file uboot.bin to NAND flash 0 up to offset 0x00074000 in 75s.
The green LED is on and so is the blue LED.
So far so good.
At the beginning of this procedure it is said to unplug and replug the minisusb cable after uboot.bin is written. The same is stated in the tutorial "Afterwards the Windows version beeps; you need to unplug your mini usb cable, plug it back again and open the terminal[...]"

My first problem is, there is no beep. So I thought "it is said... 'after uboot.bin is written...' " which obviously is the case - I unplugged the miniusb. There was the standard windows sound which occures after inserting or removing USB devices (is this meant by beep?). But then the command line of Windows was flooded by communication error messages. I used CTRL+C to exit it and tried to connect with Putty. Still the same black screen I had directly after the brick.
I started all over starting with "runme.exe nand" but this time I waited 10 minutes after "wrote file uboot.bin" and still no beep. So I unplugged the mini usb cable again and it's the same error message flood. This time I did not exit the command line but tried to connect with putty. It worked but there was the same message flood with unreadable characters. Looked like a wrong encoding, so nothing readable.
I started all over again... and this time I waited more than 30 minutes. There were 2 addition lines after 30 minutes: "Error: invalid mode value encountered 0" and "Error: cpsr contains invalid mode value - communication failed". After 5 more minutes it continued with "[...]cpsr: 0xffffffff pc: 0xffffffe9"
MMU[...]
and again both of the errors.
-----------------
After the last lines (I guess the sheeva was on for 45 minutes) I cancelled the command line again (with CTRL+C) and unplugged/replugged the miniusb. This time putty worked (after pressing the Enter key once - didn't work before!). Everything is back to normal - and with the latest uboot I intended to install (and because the Sheevaplug bricked).