Lavamat 74620-W door problems

Hi,
I own a AEG Lavamat 74620-W product number 914001304

The washing machine works fine except for two things;

1) The door does not unlock at the end of a wash cycle (it requires the emergency release by the pump drain)
2) The door automatically locks as soon as the wash program selector is turned. Previously it locked when the START button was pressed

There are no error codes shown on the display.

I have removed the door lock and tested the three connectors with a meter. Both of the two pin connectors which I assume are switch interlocks seem to be opening and closing with the operation of the lock. The three pin connector that I guess is the door lock activation solenoid has sensible resistances across it.

Next I checked the pressure switch the pipe connecting it to the drum is clear. When I connected a syringe to the pressure switch I could hear it switch. (open & close with pressure changes)

I suspect the electrical functions of the pressure switch are ok, as I have no error codes and the machine is working and not flooding ?

I am left thinking that the door locking problem must reside on the main control board. As the control board thinks there is nothing wrong, but is itself sending a faulty “always lock” signal to the door lock.
I have removed the main control board and there is no obvious signs of damage to components. It looks like the door switch is driven by a Triac and a relay.

A few Questions.
1) Is it likely that a faulty Triac could be the cause of the problem.

2) Its difficult to buzz the board through with a meter does anyone know how the Door solenoid is activated for a 74620 ?

3) I have read on some forums that AEG store extra “internal” error codes that can be accessed by pressing certain buttons, anyone know if this works with a 74620

Any other help or ideas would be greatly appreciated.