Ford mondeo boot won't open off of dash button or boot handle but will from key fob?

I have a 2001 ford mondeo estate and I can't get the boot to open from the dash button or the boot handle but I can from the key fob by double pressing it.

I have tried removing the dash burron and reconnecting it with no success

this seems to be a common problem on this car yet nobody seems to know the cause

Disconnect the boot button, see if the dash now works. Get a new switch.

Why it happens:
the boot button gets wet, shorts out and effectively continually sends the open command, the system can't see any the button press form the dash button because it's the same wire.
In the unusual event that it still doesn't work then the wire in the tailgate is damaged, near the hinge, shorting to earth.