username: root
password:
so enter root and when it asks for password press enter
This is actually a problem with xdm, that I observed when setting my rootfs. If you have a username with an empty password, like in this instance, xdm will NOT login, i.e. you get the login incorrect.
That's why I set the root's password to root in my rootfs, specifically to overcome this. Anyhow if you logged in once, you should've changed root's password anyway, that should be automatic and not login as root with an empty pass.
To solve your problem:
Mount the SD card on a linux pc.
In /etc/rc2.d rc3. rc4.d and rc5.d rename S99xdm to K01xdm
Then you can boot on the Uni. X will not start. CHANGE THE ROOT'S PASSWORD. Then rename all the K01xdm files back to S99xdm.
Reboot. X will start. You will be able to login normally.