That is a "spanner" screw, not to be confused with the UK term spanner as in a wrench. They have tips that fit the two holes and come in different sizes, but they are very rare and I'd have to guess that the person who closed it up last was an elevator repairman because that's the only place I know where these screws get used regularly.
To get them out you could buy the right driver, but another trick is to use some really narrow needle nose pliers in the two holes and slowly work it around. The only other thing I could suggest is drilling through it, but I can't recommend it because I don't know how close the electronics are under the cover.
Here's a link to the kind of driver tips I'm talking about...
http://www.hudsonfasteners.com/sec/sec_sp_scrdrvr.htm
...and if you get them out I would replace them with something more standard, but I'm sure the frustration has already made you come to that conclusion yourself ;)