Berlingo Mk1 keyfob

Hi, I have a 1998 Berlingo. I have a niggly problem with my keyfob. Mabye somebody knows how to sort this out.

I got a 2nd hand ignition as the old one was worn with a new key. I replaced the electronics board and the chip inside the new key with the board and chip from the old key. This works fine. The immobilser accepts the new key ( and new ignition).

The problem with the electroncis board is that the button that activates the locking mechanism was worn. I replaced that with a new button that I soldered on. This seems to work as each time I press the onbaord LED light activates.

However, the locking mechanism is not responding.

Does anyone know if this scenario requires reprogramming of the chip or the electronics board and where can you get this done for how much approximately?

I have investigated this a bit on Berlingo boards and they talk about reprogramming for the immobiliser. However, the replacement key works fine with my immobiliser but NOT with the central locking.

The manual also mentions that in order to re-link the key to the immobiliser after batteries have been replaced it must be placed into the ignition the motor should be started and then the button must be pressed. I did all that but the central locking still doesn't respond.

There are two possible scenarios i can see here:
I might have Physcially damaged the board while soldering ( but I don't know how to chekc for that ) or the integrated chips require some form of resetting after the heat from the soldering iron.

any advice appreciated. It would stop me from messing around with two keys.