Did you do a factory reset after changing the battery? Power loss results in crazy values being stored in the audits. Do a factory reset and specifically check the values in the sound settings afterwards.

When you say sound test works fine, do you mean a sound test triggered by a button on the sound board or the one from the audits menu (not familiar with HMM or which sound board it has), if the former, suspect MPU IDC connectors (if factory reset followed by making certain correct values are stored in the sound settings doesn't help).