there is a flashing key its holding "u" while the device is booting from a cold boot (taking out the battery)

however there isnt much you can to do without the usb port (as its needed for flashing)

you could try to resolder the connector
http://talk.maemo.org/showthread.php?t=54762&page=2 post number 12

or use the usb connector behind the battery (careful as this port has no current protection)
http://talk.maemo.org/showthread.php?t=71414

after you get a port working you could try to just flash the kernel see the wiki for the instructions on using the flasher

Good Luck!