Why not just power it up with a 12v power supply, my m8 wanted a illuminated oddy x bell putting up. Did tell him to get alarm but wasnt for having it

Just put 12 volt wire a hard poss onto u bell trigger leave battery disconected as u know someone gonna eventually unplug it after 5pm lol. Then u got a realistic dummy i wouldnt even bother with a dummy or bell only for that matter tbh. there still gonna have a go, when they do u want something decent.

Have often argued a 'proper' £50 bellbox is a better investment than a £99 s**t system kit, still rubbish but at least you're not just burning money...

I've got an knackered UPS in the stores with 8x 100+ ah's in might get it to last a week or two with those in it