Itemised as not working when you bought the house was it?
Go back to the vendor and get the code.
Most if not all of any costs you might incur will be greatly reduced.
If, when you get the code, post again with the Control panel type you have it will be a Scantronic 9448 or 9448+ or 9449.
The number you have given is the KeyPad only.
Then it will be easy to help with a code change, problem solved