Hi, I have a big trouble I think, I'm a new gumstix user and I think I really mess up, I was following the manual in here, http://www.gumstix.net/Software/cat/Getting-started/111.html , but in one part  I need to use katinstall in one step, but I have to upgrade the u-boot for can use it, I follow the next manual http://docwiki.gumstix.org/index.php/Uboot in here, but when I restart the gumstix don't boot at all , don't pass from this screen 

Connecting to /dev/ttyS0, speed 115200
 Escape character: Ctrl-\ (ASCII 28, FS): enabled
Type the escape character followed by C to get back,
or followed by ? to see other options.

There's something I can do? I think this problem it's almos like mine http://sourceforge.net/mailarchive/forum.php?thread_name=dbd9700a0810051906t509853b5vc97c8f8e038bf2e2%40mail.gmail.com&forum_name=gumstix-users , or there's someway to reestablish the factory settings maybe  through the mmc card?

I hope I can find help,