Problem
Someone's set a password on the LOM user and you don't know what it is.
Solution
If you don't do anything, the LOM password prompt will eventually time out and drop you to the system console (assuming the system is on).
Log in to the system as root and:
# cd /usr/platform/`uname -i`/sbin
# ./scadm userpassword admin
Note that it will demand a "strong" password (ie 6 chars or more including at least one number), so unless you use a standard one you'll likely need to do this again in the future.