After changing in Active Directory the credentials for the RMS (BV) Query Engine Service Account used by RMS (BV) Query Engine to collect data from remote systems, all queries are failing with error : MQE failure access is denied. You have configured the RMS (BV) Query Engine Service Account in RMS Credential Database and you have forgotten or lost the password to access that database.
The Credentials Database contains the administrator level users and passwords to all your domains and systems configured there, and according to security standards you MUST know the Credential Database password in order to access it. This password and the database are encrypted and cannot be reveled or reset. The intruder, who might gain the access to RMS (BV) Administrator account might automatically gain the access to all administrator level accounts of all your domains and systems stored in the database - if that database would not be password protected and if the password to it, could be easily reset.
Once this password is lost or forgotten the Credential Database cannot be accessed and you need to create a new database. In the new Credential Database you must define all needed credentials again.
There is no mechanism and tools available at the moment, which could allow Technical Support to unlock the Credentials Database password.
In case the password to the old Credential Database might be recovered in the future and used in order to access it, then simply leave the old Database in RMS. You will then have two databases, the old one which will not be used until the password is recovered, and the new one which will be used. You will then need to assign the newly created database to entitled users.