The green fur worries me. It’s a sign that current was leaking there…which could quite possibly mean that contact got shorted to ground, which would be the end of that module on the ECU.
Agreed. I think the clue is that you said in your post of July 3rd. that you have had trouble with water in the footwell. If the ECU or plug terminals are corroded in any way at the very least they must be cleaned thoroughly. If the corrosion is severe it could well be creating a resistance between the wire and the crimp connections of the plug, not an easy matter to rectify The ECU itself may have internal corrosion which can create havoc with low voltage. I would be thinking in terms of a thorough test of the ECU and plugs.
Regards Geoff Peace.