Bosch SHX46A (6 years old) Selected

From your description, I doubt that the problem is door latch is the cause.
The first thing that a modern dishwasher does before it begins to fill with water is run the drain pump.  It appears that this DW is not progressing to the next cycle (inlet water) and because the pump runs even when the door is open, I agree that the controller card may have failed.
If possible, inspect all the wire connections (remove main power before you do this) ... if there is a loose connection, the controller could do odd things.
Good Luck!  Please report back what you find, OK?