ADP 4520 Diplomat Double Oven?

The heating element is broke in the bottom oven, I've done my research. But when I went to remove the back plate, the two screws are not budging. I've just sprayed WD40 on them both, but I don't have much faith in it doing the trick. The oven is 5 years old and the heating element also went about 2 1/2 years ago and got replaced by a engineer. With the exception of a blow torch lol, how do I do I remove the back plate?