Also, if you are replacing the batteries, I would be very careful. If you hook up the batteries the wrong way, you will blow up your panel. I did it once when I was a younger and newer technician, wasn’t paying full attention to my connections and blew a booster panel.
As well, many areas have codes regarding batteries. For my area, they need to be a certain type, have a visible date code and be less than 5 years old. Anything more than 5 years and the battery needs to be replaced. Our code is changing it to 4 years very shortly too. So make sure they fall into the right category and work as intended.
I have seen building managers fined and put in jail because they decided to change the batteries, didn’t test them or got outdated ones, fire happened, fire alarm didn’t work because batteries were dead, and someone died.