Octavia 1600 petrol

Customer brought this in, intermittent non start and battery going flat. AA tested and condemned battery. New battery now fitted and tested ok.

About 20 minutes after the engine is turned off, the cooling fans start to run. Initially we found the engine control relay was hot, also fault code 17069 - PCM power relay open circuit.
We replaced the relay and cleared the DTC which has not returned. Starting now seems ok.
But fans still coming on about 20 minutes after switching off and locking the car. These continue to run until the battery is flattened.

visibly the wiring looks good. No chafing anywhere etc.

Is this a problem anyone else has had?