i would highly suggest staying away from a used one as you will have no idea the condition of the used module, and a new module would be the decision of choice. One thing u can attempt,which has been successfull for me in the past, unplug the DDM and leave it unplugged for a few hours to reset and plug it back in to see if resetting the module resolves the concern. Sometimes the modules logic gets corrupted and by resetting the modules it resolves the issue. If resetting the module does not resolve your concern i would suggest installing a new module. Reprogramming will not be beneficial in this case

it does not make a difference, but i would suggest with the power off. That is the procedure i always follow as to prevent voltage from spiking when the module is unplugged

the only way to properly reset the module is to remove all power and ground from it and that would involve removing the door panel to access and unplug each connecter to it. please allow me a few minutes to aquire the part number for you ,as i will need to run the vin number through Ford's database and then consult my parts department. i will post the reply shortly, probably will take about 5 minutes