"lockfile" just refers to a file that is readonly...
http://linux.about.com/library/cmd/blcmdl1_lockfile.htm
... the name would be specified by the shell script running (somthing.lock).
If you are still using sudo that might be the source of your current problem. Redhat distros do not normally come with sudo setup. Just boot normally (run lvl 3 or 5) and login as root. Remember that the command to is "su -" the - enters you into the environment of the user you are switching to. (su = switch user) A default user will not have /sbin in their enviroment... normally. I admit I do not have much experience with RHEL.
Just out of curiosity, why is you need to update the bios anyway?