old uboot update (3 replies)

hi,
i have some goflex net with the doozan uboot from 2010.
U-Boot 2010.09 (Oct 23 2010 - 11:53:10)
Marvell-GoflexNet by Jeff Doozan, Peter Carmichael

unfortunately there is no rescue in flash and i dont have an old debian usb stick (ext2 lenny i think) anymore.

so i cant boot anything to update the uboot and use a new debian system.

how can i manage to update the uboot?
i have a serial cable and an tftp server.

tia
jay