I am in the process of attempting to install an outside switch for a radon mitigation system. However, I am unable to drill through the remaining part of the block wall. I have an M12 Fuel hammer drill and a carbide drill bit. I imagine something is in the way but what? If it was concrete in the floor I would guess rebar. The first part went through like butter. I have pictures: https://imgur.com/a/hCed4u8