I recently got my car back from the shop and the brake lights no longer work. I have tried to open the fuse box under the hood to check fuses. However, I can't seem to get the box open. Both knobs turn about a quarter of an inch and that is it. What do i need to do to get the cover off the box?? Also, any other suggestions about the brake lights. All other lights still work, hazards, turn signals, and headlamps. I cant seem to find anything else wrong. The shop just changed fluids and worked a little on a vacuum problem. I am relatively new to the mbs and am still getting my feet wet. Any help is much appreciated.
car is a 1978 300D electric windows still work as well

thanks