I had a similar problem with mine. However, the broken wire was not where it attaches to the keypad, but about an inch further up the loom. I had to unwind the loom cover to find it. I had two broken wires, one orange and one red. This was fortunate as there is only one red wire and the others are all orange. How many of your wires were broken and what colour were they? If there is more than one broken orange wire, have they been reconnected in the right order.
It may also be worth looking at some Citroen and Peugeot forums as this is a common problem and the keypad was fitted to many of their cars.
You don't mention whether you have petrol or diesel. If it is petrol, you have to get the keypad working before you can disconnect it. If it is diesel, I believe you can bypass the immobiliser with a feed to the fuel pump.
Another thing to be aware of is that while my immobiliser was malfunctioning, the relay to the ecu was constantly cutting in and failed soon afterwards. It may be an idea to disconnect the battery to prevent this, or carry a spare relay.
Good luck.