the point about if it wiggled about and then works, it's down to the connection, so check it's prongs and fitment.
My advice would be to unplug the ecu from the passenger foot well and check the resistance's on the wiring which heads back to the CTS. if this checks out ok it would be advised to check the pin connections on both the plug and the ecu for good connectivity. There are no known issues with ECU failures to press but that doesn't mean it cant happen. But going by what your dealer has said by moving the wires etc the fault goes its a connectivity issue rather than an ecu fault.
For information the ecu's were removed on the cars for reflashing so it could be that there has been either a wire broken/trapped etc or the pins misaligned causing future issues.
I have no service manual to hand on this laptop so cant tell you wiring colours and pin numbers at present. I can check this back at the workshop on Monday.
Hope this information assists. Its back to basics really with the wiring and resistance checks and continuity to grounds