Removed the outside cover. And yes-the two bottom screws on the back are pinned, security screws. If you don't have the tool (and don't want to go out to buy it) just use a small hack saw to cut a slot in it so you can remove it.
The repair was complicated by the fact that the oven is cabinet-mounted. So, extra work was required removing the ducting and outside case. Make sure the cover locks back onto the front frame when done. There are overlapping edges that should interlock. You don't want extraneous microwaves leaking out. Also make sure ALL screws are back in their proper holes so everything is buttoned up.
For the small cost I also replaced the fuse while I was in there as the old one was 10-yrs old. Bought that here as well. Why not do that while you are in there?