We are running into issues with performing backups using ABU.
Only thing I can think of is if the password in question has a character that doesn't work with the configuration script. I would try to avoid passwords containing dollar sign, single, or double quote characters. Suggest test with a plain password containing just numbers and letters (first character a letter).
FYI, you should be able to rerun the configuration script targeting just the RDBMS login details with the "-au" switch