veritas 8 (r8) not setting?

My flat has a Veratis 8 (R8? whats the difference) fitted.

The alarm goes off everytime a lamp blows in the flat, do I assume they are on the same fuse??

Had a power cut recently and alarm went off, engineer called as someone had obviously seen/ heard alarm. He disconected main fuse on PCB and checked battery.

Battery was u/s so I obtained a new battery, fitted it, changed code, done a walk through test and all appears ok.

However when I try to set the alarm, it make a double beep noise continually beep, beep pause beep beep etc and eventually the alarm goes off.

The unit is also making a loud humming noise constantly.

Are these related, any advice would be gratefully appreciated.

I have both user and installation manuals from the web

Thanks guys