startbfa.sh has old password file and causing TSO userID/Password to be revoked
One answer
My guess is that it's not the password in startbfa.sh that is giving you grief. Because it's your TSO id that is getting revoked, I would guess that your old password is in the build engine definition on the server. You'll need to update the Build Agent tab with your new password.
The reason it's trying repeatedly and continuously locking your TSO id is because the "Monitor last contact time" box is checked on the Overview tab of the build engine definition. If you deselect that, it should slow down the lockouts.
The user id / password file in the startbfa.sh file are actually a repository id, and are used during the fetch to communicate from the build machine to the repository. Since it's your TSO id that's being locked, it's unlikely that this is the id causing the problem.