How to change the ccm

[marcus]

Passat B5 1.8T 20V petrol Saloon B5 chassis

Central locking not working in that none of the door locks actuators open or close with the remote. . Initially became intermittent then odd doors would work some wouldnt and now none work. (Everything else ccm related is working fine, boot lock, alarm, interior lights, siren..)

I have the passenger carpet up the wiring looks ok so want to try a ccm swap have a replacement same part number from ebay.

What is the procedure for switching the ccm do I need to disconnect the battery before unplugging it and putting the new one in. I have Ross-Tech so can recode the keys

Welcome any thoughts