ADT dummy box more of a deterrent than a working system? If that was the case hardly anyone would fit a system.
[Logan: ADT is whole different topic you can't compare a national to a local like that, start that topic somewhere else, please]
Considering the knowledge you have shown about the components and operation (areas/zones) of the system and my experience giving advice here, you'll probably struggle to DIY.
Minimum requirement will be batteries (probably replacing the bell at the same time) system checks with a multimeter (knowledge how to do these), walk test, beel test, operation checks etc etc.
Even then you will have to hope the programming is to your liking, otherwise you'll have to learn how to program a system with limited access to manuals or the terminology in them.
Someone that knows how to program a Menvier could likely recommission everything in less than an hour.
Consider all this before you leap at the task of DIY, your playing with a safety system that could annoy your neighbours when you can't shut it up in the early hours, you've then lost some of your deterrent factor.