-So you have toggled the bit to try and see if it will turn off?
-changed the address location in case the o/p has been fudged?
-Even changed the o/p for the direction gong to not o/p to see if this changes anything?

Good work here, but I wonder if there is a funny logic that is switching it on permanently ie what about fire service/recall, independent service, even a software issue? I would go thru the imputs and switch/disconnect them all off and see if this changes the arrow state. other than that the only thing left is either a wiring issue hard on(don't think this is true) or a serial data issue( cant remember if it is serial but I think so, so check for bus resistor failures).