[U-Boot] Killed Sheeva Plug

[Norbert Wegener]

Hello
Let me first say that I am *completely* new to U-Boot.
I have a Sheeva Plug with a board Rev1.3.

While trying to learn about it, at the U-Boot prompt I issued a command
I'd better not issued:
nand erase
It seems, U-Boot did what I asked to do...
No U-Boot prompt any more and nothing else:-(

Is there any description available on how to bring it back to life?
Do I need additional hardware to do so?
I read about a JTAG board in this context.
Is such a thing necessary?
You see, I am really not familiar with this topic.
Therefore any advice would really be appreciated.

Thanks in advance
Norbert Wegener