The "Nintendo" would become a black rectangle* due to correctly decompressing different data (from the open bus read), the "®" and the "Game Boy" come from the console, in any case
something gets displayed
* talking about GB/C mode of course, GBA modes usually hides the loaded logo and the ® when no card is inserted but I don't know the specific details
Dunno, should be a bit like this:
View attachment 395756
But certainly they should all look the same - at the same time, due to the above, it seems the slot is not the only or even the main problem...
As for the switch I don't remember the exact pinout but it should be on gbatek