as far as i know there isn't a way that the strength of the password complexity would be stored on an EEprom on board the machine. You're not stating as such, but you did destroy the previous RAID configuration and created a new one?
Just to be sure, you drop in the CD / USB with the download Server installation and you are formatting the drives it finds during the install wizard?
In general passwords should be at least 8 characters and have 3 of 4 type-subsets (high/low caps, numbers and special characters are the subsets). The passwords you've tried have been at this level or above?