So when you turn it on are the correct lights comming on for the cycle you select?
When you press start will the door lock so it cannot be opened?
Ok when you press the start button does it feel normal like the other buttons of is it loose?
As sometimes the plastic start button can break inside.
Ok lets try a test cycle and see what happens on this.
Turn the dial to off.
Then turn it to the drain cycle.
Then press the rinse hold button twice
Then press the intensive rinse button twice.
Then press the start button once.
Now it will run a test cycle. If it failes on there then you should get an error code on the display.
Try that and see what happens and let me know.
Ok if its not starting then its either down to a faulty door lock or the control board.
To check which it is you need a multi meter. Open the door and remove the metal clamp around the edge of the door seal and unlip it.
Then remove the 2 screws holding the door lock and pull it through the door port hole.
Remove the wires on the lock and there you will see 3 tags. You need to test between all 3 tags and you should get a reading between 2 of them. If you dont get a reading then the door lock is faulty and will need to be replaced.
But if the door lock checks out ok then im afraid you are left with a faulty control board which is very expensive to replace and sometimes not worth fixing.
But check the door lock first and see what you find as it may just be this at fault here.
Ok if the lock was faulty and its been replaced and it still isnt working then its more then likely the timer unit at fault here. As some times when the door lock fails it can take the timer unit out. Its not often this happens but it can happen and from the sounds of it this is the issue here.
Sorry but it looks like the control unit is faulty as well im afraid.