protec 6300 advice

Hi think i no the answer but a second opinion always helps.
Im a fire engineer with 10 years experiance
I had to replace some standby batterrys on a protec 6300 earlier this week but have now got auxfuse/batterys dissconnected fault on the panel.
I recall this happening many years ago on another site im sure i had to get hold of the 6 monthly high access code and go into the settings to change the psu from external to internal and the fault cleared
Can anyone confirm this

thanks