I am replacing my Honeywell thermostat. I removed the old one and there is a metal plate inside the drywall cutout that the old one was screwed to. I need to remove the plate because the screw holes don't line up with the ones on the new thermostat and if I try to drill holes for the new one I will be hitting the plate once I get through the drywall. The plate seems loose and I don't feel any screws holding it on. How might it be attached? Thanks.