Kev Seanor has told me there is a little red button on the right hand side of some Duke ovens . this is a reset button for when the oven / proofer has over heated and has cut out the power . 


if your oven over heats and cuts out you can hold down this button for a few seconds and the oven will reset its self. 


i dont know if every oven has one of these and i dont know if it works for any other issues apart from over heating but its definitely worth knowing if you have this button on your oven?