UK Based - Ring Video Doorbell 2nd Gen - Hard Waired


I have purched Ring Video Doorbell 2nd Gen for my mother and we had someone fit it however at the moment it is not wired up.

They are going to look at using the existing doorbell wire to connect it.

I have watched the various videos and guides about if its a mechanical or digitcal doorbell …etc but just getting a bit confused.

If the current doorbell is wired can the person installing it use a multimeter to test output and what would it need to be as a minimum?

If this is below the minimum or the doorbell is battery powered what options are there to get this wired up?

Finally if we do not go with wired up can we get additional batteries for this version and charged them ahead of time?

Many thanks,